Conclave Sledge-Captain is a rare Creature — Elephant Soldier card from March of the Machine Commander (MOC), collector number 36. Current market price: $1.52, TCGplayer market prices via Scryfall.
Backup 1, backup 1, backup 1 (When this creature enters, put a +1/+1 counter on target creature. If that's another creature, it gains the following abilities until end of turn. Each backup ability triggers separately.) Trample Whenever this creature deals combat damage to a player, put that many +1/+1 counters on it.