Pyromancer's Rage

Cast only when target creature you control blocks or becomes blocked. That creature gets +4/+4 until end of turn. Then, if it would deal enough combat damage to destroy a creature this turn, deal X damage to each player, where X is that creature's power.
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"What, you think she's gonna do somethin'? Look at her, weak little fire starter. Watch this."
- Mercenary Lloyd, Last Words