Reptile, Last of the Saurians

Wither (This deals damage to creatures in the
form of -1/-1 counters.)
Commander Ninjitsu {b}{g}{u} ({b}{g}{u}, Return an unblocked attacker you control to hand: Put this
card onto the battlefield from the command zone
tapped and attacking. This ability is affected by commander tax.)
Whenever this creature deals
combat damage to a player, create that many
Acid Pool tokens.