Goblin Kaboomist

At the beginning of your upkeep, create a colorless artifact token named Land Mine with "{R}, Sacrifice this token: This token deals 2 damage to target attacking creature without flying." Then flip a coin. If you lose the flip, this creature deals 2 damage to itself.

The List

Magic 2015

At the beginning of your upkeep, put a colorless artifact token named Land Mine onto the battlefield with "{R}, Sacrifice this artifact: This artifact deals 2 damage to target attacking creature without flying." Then flip a coin. If you lose the flip, Goblin Kaboomist deals 2 damage to itself.

The Land Mine tokens have the ability even if Goblin Kaboomist blows himself up or otherwise leaves the battlefield.

You flip the coin after the Land Mine token is created, not after you sacrifice a Land Mine. The token is created even if you lose the flip.