Soulherder

Whenever a creature is exiled from the battlefield, put a +1/+1 counter on this creature.
At the beginning of your end step, you may exile another target creature you control, then return that card to the battlefield under its owner's control.

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Kaldheim Commander

Whenever a creature is exiled from the battlefield, put a +1/+1 counter on Soulherder.
At the beginning of your end step, you may exile another target creature you control, then return that card to the battlefield under its owner's control.

Modern Horizons

If a creature is exiled but ends up in another zone (most likely because it’s a player’s commander in the Commander variant), Soulherder’s first ability triggers.

If a token is exiled this way, it will cease to exist and won’t return to the battlefield.

If any other abilities you control trigger at the beginning of your end step, you choose the targets for all of them as they’re put onto the stack, and you choose the order they’re put onto the stack. For example, this means that you could exile a creature put onto the battlefield by an unearth ability (and then unearth’s delayed triggered ability won’t exile that creature), but you can’t target a creature that will be returned to the battlefield by another ability during your end step (such as Astral Drift’s delayed triggered ability).

Once the exiled creature returns, it’s considered a new object with no relation to the object that it was. Auras attached to the exiled creature will be put into their owners’ graveyards. Equipment attached to the exiled creature will become unattached and remain on the battlefield. Any counters on the exiled creature will cease to exist.