I'm writing this first part under the assumption that people have a basic understanding of how effects that activate when something happens differ from those that activate if something happens.

This isn't a comprehensive guide, but more of a refresher as to how things work.

Some people refer to it as "missing the timing", which is wrong because that's actually not official terminology, nor does it really explain what's going on.

Anyway, for an effect that optionally activates when something happens, that something must be the last thing to occur in the game state, or else that effect won't activate.

An example is the effects of most Yang Zing monsters that activate when they are destroyed while under your control. If their destruction isn't the last thing to happen, those effects can't be activated on a new chain. If those effects were mandatory, or if they were worded with the "if" instead of the "when" clause, then those effects could be activated.

This distinction leads me to the real meat of this article, which is how chain building works in general. Understanding how to build chains is crucial to understanding much of the rest of this game.

Basics of Chain Building

I'll assume you know about things like Spell Speeds and the differences between certain types of effects. If you don't, go read the rulebook.

Also, chain building abides by Fast Effect Timing. If you're not familiar with that, go read the Fast Effect Timing rules on Konami's website.

Anyway, chains are built by activating effects of equal or greater Spell Speed than that of the previous effect. The right to act alternates between players, as per Fast Effect Timing. When neither player wishes to add to the chain, that's when you begin resolving. Note that you cannot interrupt the building or resolution of a chain with a Trigger Effect whose activation condition was met during the building or resolution of that chain; you must wait until that chain has fully resolved before starting a new chain. Remember the rules on optional "when" vs "if" triggers.

Example of a Chain

Turn player activates Dark Hole. The opponent chains Magic Jammer, paying its cost. The turn player chains Seven Tools of the Bandit, paying its cost. The opponent doesn't have a response, nor does the turn player, so the chain resolves in the opposite order it was built.

TP Dark Hole CL 1
OP Magic Jammer CL 2
TP Seven Tools of the Bandit CL 3

Resolve

TP Seven Tools of the Bandit negates the activation of Magic Jammer and destroys it.
TP Dark Hole resolves, destroying all monsters on the field.

The above is an example of a basic chain, but it highlights a couple things. First, the effect on chain link 1 is Dark Hole, which is Spell Speed 1 by design. The effects on chain links 2 and 3 are both Counter Traps, effects with Spell Speed 3. In this chain, the opponent could have also used a Spell Speed 2 effect in response to the activation of Dark Hole (such as Compulsory Evacuation Device). But in the above chain, the turn player couldn't chain a Spell Speed 2 effect to the activation of Magic Jammer (a Spell Speed 3 effect).

Advanced Chain Building

In the above example, neither player could interrupt the building or resolution of that chain with that of a Trigger Effect whose trigger was met during that chain's building or resolution. So for sake of argument, let's say one of the players had a Continuous Spell Card face-up whose effect triggers when a Trap Card is destroyed (from anywhere). That effect couldn't activate and resolve before the rest of the chain resolved. It would have to wait until after that chain in order to activate and start a chain of its own.

Knowing this is crucial in exploiting the differences between optional "when" and "if" effects. For example, let's say I want to nuke my opponent's monsters, but they have a bunch of Yang Zing monsters. I don't want them to just summon a bunch of other monsters. So what I do is Normal Summon Satellarknight Deneb and activate its effect; my opponent has no response, so I chain Torrential Tribute. With no other responses, the chain resolves backwards, with the last thing to happen being Deneb's effect resolution. Because all those Yang Zing monsters were destroyed as not the last thing to happen, their effects won't activate.

Differentiating Actions with and without Spell Speed in Relation to Chain Building

The above example highlights something else I'd like to discuss in this article, that being the difference between responding to actions without Spell Speed, and responding to actions with Spell Speed.

For actions without Spell Speed, the game state remains at that moment in time as the "last thing to happen" until the game state has passed beyond that point, such as through the complete resolution of a chain. So since Normal Summoning is an action without Spell Speed, I can activate Torrential Tribute on a higher chain link than just the one immediately following the successful summon (CL 1). But for actions with Spell Speed, if something else happens after that action, it's no longer "when" that action happened, so effects that require a response to that kind of action when it's conducted can't be activated in response to that action from here on (with one exception, but more on that later).

Example

The new Burgesstoma cards from Korea are actually an excellent example of the point here, because they have optional Quick Effects that activate in the Graveyard when a Trap Card on the field is activated. Note that these are neither Trigger Effects nor mandatory Quick Effects. This distinction is important for two reasons. For the former, it means that they don't have to wait until the whole chain is done resolving; rather, it means that their effects activate directly in response to the activation of that Trap Card. For the latter, it means that you can only do this once per Trap Card activation, instead of activating as many as you possibly can. Also, note that all of this abides by Fast Effect Timing.

My opponent activates Reckless Greed on CL 1. I chain the effect of Burgesstoma Canadia in my Graveyard. If I have other Burgesstoma cards in my Graveyard, I can't activate their effects at this time. My opponent has no response. Now even at this point, I still can't activate those other Burgesstoma effects. So if no other responses, the chain resolves backwards as usual.

Now, what if I activate Reckless Greed instead of my opponent? Well, we still go by Fast Effect Timing. Because of this, I don't get to interrupt with the activation of a Burgesstoma effect until my opponent indicates that they have no response. So if my opponent chains Maxx "C" to the activation of my Reckless Greed, I can't at that point activate the effect of my Burgesstoma Canadia, as there's no Trap Card activation on the previous chain link.

The exception to that is with mandatory Quick Effects. Let's say my opponent controls two Doomcaliber Knights and I activate the effect of Madolche Magileine on its successful Normal Summon. My opponent is obligated to activate both of their Doomcaliber Knights' effects because they're both mandatory, and this is done before either of us get the right to respond with something else. Because my opponent was the last one to activate an effect, I get the right to respond to the effect activation of the Doomcaliber Knight on chain link 3. From here, we follow proper Fast Effect Timing and chain resolution, but here, note that since the Doomcaliber Knight on CL 3 is not directly following the activation of Madolche Magileine on CL 1, that this chain link resolves without effect. The effect of Doomcaliber Knight on CL 2 is what will negate the activation of Magileine's effect and destroy it.

Hopefully this article has given you some insight on some more in-depth nuances of chain building and interactions. Let me know if you have any questions or concerns in the comments.

Useful info @Argor, do you happen to have any other examples of non spell speed optional quick effects? That part is a bit foggy to me.

LoudFist wrote:

Useful info @Argor, do you happen to have any other examples of non spell speed optional quick effects? That part is a bit foggy to me.

Quick Effects have a Spell Speed of 2, so I'm not sure what you're asking here.

Argor42 wrote:

LoudFist wrote:

Useful info @Argor, do you happen to have any other examples of non spell speed optional quick effects? That part is a bit foggy to me.

Quick Effects have a Spell Speed of 2, so I'm not sure what you're asking here.

Ow my bad. I am not that foggy, just worded it poorly.
I meant situation where optional Quick effects are activated in response to actions without spell speed. 
It's this bit below that is kinda confusing..

Argor42 wrote:

Differentiating Actions with and without Spell Speed in Relation to Chain Building

The above example highlights something else I'd like to discuss in this article, that being the difference between responding to actions without Spell Speed, and responding to actions with Spell Speed.

For actions without Spell Speed, the game state remains at that moment in time as the "last thing to happen" until the game state has passed beyond that point, such as through the complete resolution of a chain. So since Normal Summoning is an action without Spell Speed, I can activate Torrential Tribute on a higher chain link than just the one immediately following the successful summon (CL 1). But for actions with Spell Speed, if something else happens after that action, it's no longer "when" that action happened, so effects that require a response to that kind of action when it's conducted can't be activated in response to that action from here on (with one exception, but more on that later).

LoudFist wrote:

Argor42 wrote:

LoudFist wrote:

Useful info @Argor, do you happen to have any other examples of non spell speed optional quick effects? That part is a bit foggy to me.

Quick Effects have a Spell Speed of 2, so I'm not sure what you're asking here.

Ow my bad. I am not that foggy, just worded it poorly.
I meant situation where optional Quick effects are activated in response to actions without spell speed. 
It's this bit below that is kinda confusing..

Argor42 wrote:

Differentiating Actions with and without Spell Speed in Relation to Chain Building

The above example highlights something else I'd like to discuss in this article, that being the difference between responding to actions without Spell Speed, and responding to actions with Spell Speed.

For actions without Spell Speed, the game state remains at that moment in time as the "last thing to happen" until the game state has passed beyond that point, such as through the complete resolution of a chain. So since Normal Summoning is an action without Spell Speed, I can activate Torrential Tribute on a higher chain link than just the one immediately following the successful summon (CL 1). But for actions with Spell Speed, if something else happens after that action, it's no longer "when" that action happened, so effects that require a response to that kind of action when it's conducted can't be activated in response to that action from here on (with one exception, but more on that later).

Well although the main example I used involved summons, attack declarations are another example. So if I declare a direct attack with something and activate MST on CL 1 in response to the attack declaration, my opponent can still activate Swift Scarecrow in chain, as it's a Quick Effect and we're still at the moment in time at which I declared a direct attack.

Also, note that the moment in time in which a monster would be summoned is another exception to this, as you can only activate an effect that negates the summon as CL 1 (but then, "would be summoned" isn't an action, but rather a moment in time preceding a successful summon).

Argor42 wrote:

LoudFist wrote:

Argor42 wrote:

LoudFist wrote:

Useful info @Argor, do you happen to have any other examples of non spell speed optional quick effects? That part is a bit foggy to me.

Quick Effects have a Spell Speed of 2, so I'm not sure what you're asking here.

Ow my bad. I am not that foggy, just worded it poorly.
I meant situation where optional Quick effects are activated in response to actions without spell speed. 
It's this bit below that is kinda confusing..

Argor42 wrote:

Differentiating Actions with and without Spell Speed in Relation to Chain Building

The above example highlights something else I'd like to discuss in this article, that being the difference between responding to actions without Spell Speed, and responding to actions with Spell Speed.

For actions without Spell Speed, the game state remains at that moment in time as the "last thing to happen" until the game state has passed beyond that point, such as through the complete resolution of a chain. So since Normal Summoning is an action without Spell Speed, I can activate Torrential Tribute on a higher chain link than just the one immediately following the successful summon (CL 1). But for actions with Spell Speed, if something else happens after that action, it's no longer "when" that action happened, so effects that require a response to that kind of action when it's conducted can't be activated in response to that action from here on (with one exception, but more on that later).

Well although the main example I used involved summons, attack declarations are another example. So if I declare a direct attack with something and activate MST on CL 1 in response to the attack declaration, my opponent can still activate Swift Scarecrow in chain, as it's a Quick Effect and we're still at the moment in time at which I declared a direct attack.

Also, note that the moment in time in which a monster would be summoned is another exception to this, as you can only activate an effect that negates the summon as CL 1 (but then, "would be summoned" isn't an action, but rather a moment in time preceding a successful summon).

Got it, thanks =]