If you flicker a creature with a 'when this enters the battlefield' trigger, does the trigger go on the stack immediately?

When a creature with a 'when this enters the battlefield' (ETB) triggered ability enters the battlefield, the trigger is first created at the moment the creature enters. However, it does not go on the stack instantaneously — it is placed on the stack the next time a player would receive priority, after the current spell or ability has finished resolving. This is governed by CR 603.2 and CR 116.5.

So if you cast a 'flicker' effect like Ephemerate, here is what happens: Ephemerate resolves, exiling your creature and returning it to the battlefield. Only after Ephemerate has fully finished resolving does the game check for triggers. The ETB trigger is then placed on the stack, and then players receive priority. Neither player can respond during the actual resolution of Ephemerate before the creature re-enters.

This matters because state-based actions are also checked before triggers go on the stack after a spell or ability finishes resolving (CR 704.3). So the sequence is: spell/ability resolves → state-based actions checked → triggered abilities go on the stack → priority is passed.

Concrete example: You control a Mulldrifter and cast Ephemerate targeting it. Ephemerate resolves fully — Mulldrifter blinks. Now, after resolution, the ETB trigger ('draw two cards') is placed on the stack. Only then do players get priority to respond to that trigger (e.g., by casting an instant).

The key rules to remember are CR 603.2 (triggered abilities trigger when their condition is met, and are placed on the stack later) and CR 116.5 (a player receives priority after a spell or ability resolves, after state-based actions are checked and triggers are placed on the stack).