the weather thunder canvas

[Dr. zoidberg]

if the defending player activates this trap, then pays its cost that it grants the monster in adjacent zones, the effect and i chain time thief retrograde, which card becomes material?

[Unorthodoxical-Princ]

"The Weather Thunder Canvas":

"The Weather" Effect Monsters in your Main Monster Zones of this card's column and its adjacent columns gain this effect.
● At the start of the Damage Step, if this card battles an opponent's monster: You can banish this card; return that opponent's monster to the hand.
You can only control 1 "The Weather Thundery Canvas".

"Time Thief Retrograde":
When a Spell/Trap Card is activated while you control a "Time Thief" Xyz Monster: Negate the activation, and if you do, attach that card to a "Time Thief" Xyz Monster you control as material. You can only activate 1 "Time Thief Retrograde" per turn.

A couple of points. You can only activate "Time Thief Retrograde" when a spell/trap card is activated, just as it says on the card. The activation of a card is as follows:

Either from the hand to the field, from set position to face-up position on the field, or through a card effect, such as something like "Metaverse". Those are all examples of activating a spell/trap card. However, if a trap card is already on the field and you are activating its effect, then that is just the activation of the trap effect, which is not the activation of the card itself. The only way you would be able to chain "Time Thief Retrograde" is when they activate the actual card, "The Weather Thunder Canvas". If you activate the card by flipping it up or activating it from the hand, for example, then "Time Thief Retrograde" can be chained and you resolve the chain like normal. However, if a monster who got its effect from "The Weather Thunder Canvas" activate its own effect, then that is the effect of the monster, not the trap. "Time Thief Retrograde" cannot be chained to monster effect activation