Yu-Gi-Oh! » Rulings Q&A

Hello everyone,

I struggle to understand how timing works in goat format. Let's say my opponent starts his main phase. Can he summon a monster or change the position of a monster using his priority before I activate my set MST? Or does priority only work for card effects (e.g. if he wants to play pot of greed)?

Same question at the end of a chain, can I activate a card on resolution before he summons a monster?

Thank you

Pretty sure it's starting a phase gives turn player priority to do actions, so you would want to use Quick Effects in Standby or Draw if you want to do it before they play a card. At the end of a chain or action (such as setting a card) turn player gets priority to use Quick Effects, then the opponent does, so you can use Quick Effects before they do another action or Spell Speed 1 effect.

So in the first scenario: beginning of Main Phase he gets to summon before I use MST.
In the second scenario, a chain happened: I get to play MST before they can use ignition effect or summon a monster.

Did I get it right?

in Goat format, your opponent retains ignition effect priority and fast effect priority on the resolution of a chain

this changed some time around 06/07. For example in Edison format your opponent only retains ignition effect priority on the resolution of a chain if the last thing to happen is a summon. If the chain resolves in anything else (e.g. Jar of Greed) then they would only retain fast effect priority

it is correct that in either case, you can use a fast effect before your opponent can summon a monster though

Yes, you’ve mostly got it right! Here's a bit more detail:

[list=1:2odmmg5r][*:2odmmg5r]First scenario (Main Phase start): Your opponent has priority at the start of the Main Phase, so they can summon a monster or change its position before you activate MST. However, MST can be used in response to an effect, but not to the actual summon.
[/*:m:2odmmg5r]
[*:2odmmg5r]Second scenario (After a chain resolves): Once a chain resolves, the turn player has priority to activate an ignition effect or summon a monster. You cannot activate MST before they use their priority, unless you're responding to an effect that starts a chain.[/*:m:2odmmg5r][/list:o:2odmmg5r]
So, you can’t interrupt a normal summon with MST but can respond to card effects or effects that start a chain!