What if two 'When Play' effects are triggered at the same time?

When multiple "When you play" (Play Effect) abilities are triggered simultaneously, the order of resolution is determined by the player who controls those abilities.

According to Rule 376.3.b and Rule 376.3.b.1:

• If you control all the triggered abilities: You select the order in which they are placed on the chain.
• If multiple players control the triggered abilities: The turn player orders their triggers first, followed by the non-turn player. Each player orders only the triggers they control. Once all triggers are placed on the chain, they resolve in a "Last In, First Out" (LIFO) manner.

Key Nuances:

• Play Effects are Triggered Abilities: As defined in Rule 376.4.a, "When you play me" (for units) or "When you play this" (for gear) are Triggered Abilities.
• Timing: These abilities are put on the chain as pending items after the permanent has been finalized and has entered the board (Rule 376.4.a.2).
• Simultaneous Triggers: If multiple triggers occur at the same time, the controller(s) of those abilities determine the order of the chain (Rule 376.3.b).

This is consistent with the FAQ guidance: "If multiple players separately control Triggered Abilities that are Triggered simultaneously, then starting with the Turn Player and proceeding in Turn Order, each player orders their Triggered Abilities on the Chain."