Like Flash Foliage, this has some rules issues. You probably want to say "You may cast this spell during the declare blockers step for its ambush cost". Otherwise you can Ambush this in blocking one creature, then during declare blockers make it also block another creature.
Alternatively, and much more simply, just say "If you're being attacked you may cast this spell for its ambush cost. If you do, it's returned from the battlefield to its owner's hand at end of combat." That's the approach things like Qasali Ambusher have taken.
Thanks for the assist Alex, super helpful as always
Like Flash Foliage, this has some rules issues. You probably want to say "You may cast this spell during the declare blockers step for its ambush cost". Otherwise you can Ambush this in blocking one creature, then during declare blockers make it also block another creature.
Alternatively, and much more simply, just say "If you're being attacked you may cast this spell for its ambush cost. If you do, it's returned from the battlefield to its owner's hand at end of combat." That's the approach things like Qasali Ambusher have taken.
fixed error with Tap symbol - did say (T)
relooking at this with several new sets since I first created it, I think it is fine as curreently worded.
This is the alternate idea for Ambush (or Waylay - don't know which I prefer)