Wave 1: Wave One
Number: 39
Uncommon
8★
In that case, nothing happens.
The Infiltrate will scrap the action you played and negate its effect, but Thundercracker’s ability still triggers because you played an action.This is also true for other cards that cancel an Action, such as Jam Signals, Overrule, and Speed Trap, and for any other effects (like Thundercracker) related to playing a card.
You play one action from your hand, then you play the second, then resolve the triggers caused by those actions.