MTGNexus

Calling all rules experts! Is the following mechanic - or at least something like it - possible?

Ambush ([Cost], return a creature you control that's blocked or blocking to your hand. Put [this creature] from your hand onto the battlefield blocked by or blocking the same creature the opponent controls).

The mechanic is functional and the reminder text is clear enough. The actual rules text would be more complicated but you don't usually worry about that unless it's actually nonfunctional.

An important distinction you will want to be clear about is if returning the creature is part of the cost or part of the effect. It should be part of the cost or written in such a way that it fails if the creature doesn't return to hand.

Ambush 1B (1B, Return a blocked or blocking creature you control to hand: Put this card onto the battlefield from your hand blocking or blocked by the same creature.)

Thanks for the feedback and the templating suggestion. The way you worded it is definitely more crisp.

You'll need to say "creatures" plural in the reminder text in case it was blocked by multiple creatures.

As for when the card is the blocker, you'll need to have answer for when the bounced creature was blocking a large number of creatures, for example Hundred-Handed One or Guardian of the Gateless: is the replacement creature now blocking all of the creatures somehow, or just one? Do the rest become unblocked attackers if nothing else is blocking them?