Agate Instigator (BLC 21)

Creature — Lizard Rogue • Mana cost: {1}{R} • Bloomburrow Commander • Rare

Offspring {1}{R} (You may pay an additional {1}{R} as you cast this spell. If you do, when this creature enters, create a 1/1 token copy of it.)
Whenever another creature you control enters, this creature deals 1 damage to each opponent.

Illustrated by Quintin Gleim.