Molten Impact

Molten Impact deals 4 damage to target creature
or planeswalker. Exile Molten Impact with a
number of flame counters on it equal to the
excess damage dealt this way. For as long as it
remains exiled, it has "Whenever you cast an
instant or sorcery spell, put Molten Impact from
exile into its owner's graveyard. When you do, it
deals damage equal to the number of flame
counters on it to target creature or planeswalker."