Triggered Reactivation

Return target artifact or creature card with
mana value 3 or less from your graveyard to
the battlefield. If a creature enters this way, it
enters with an additional +1/+1 counter on it.

———{line}{line}{line}{line}{line}{line}{line}{line}{line}
Even though they are immobile, the Decayed
Guardians will still trigger to attack.