Goblin Bomb 
Enchantment
At the beginning of your upkeep, you may flip a coin. If you win the flip, put a fuse counter on this enchantment. If you lose the flip, remove a fuse counter from this enchantment. Remove five fuse counters from this enchantment and sacrifice it: It deals 20 damage to target player or planeswalker.
Legality
standardNOT LEGALpioneerNOT LEGALmodernNOT LEGALlegacyLEGALvintageLEGALcommanderLEGAL