The Dragonstorm

When The Dragonstorm enters the battlefield,
deal 3 damage to all non-dragon creatures.
Sacrifice this and 5 dragons you control: deal 10
damage to all targets. This ability can't be
countered, and the damage can't be negated.
Summoned only once in history, the Dragonstorm was
used in the Dragon War. It was a closing spell,
entirely obliterating a nation.