Helms Deep - Stronghold

{t}: Add {b}
Keep: If a Knight token creature is summoned
while Helms Deep is in play you can choose to
put that token under Helms Deep, any Knight
under Helms Deep can't be destroyed until Helms
Deep is destroyed. When Helms Deep gets
destroyed put all token creatures that were under
it on to the battlefield. (Helms Deep's power
is equal to the number of Knights under it).