Darksteel Citadel

As an additional cost to cast this spell, discard a card.

Search your library for a basic land card, reveal it, put it into your hand, then shuffle. You gain 2 life.

Activated abilities of artifacts your opponents control can't be activated. +1: Until your next turn, up to one target noncreature artifact becomes an artifact creature with power and toughness each equal to its mana value. −2: You may reveal an artifact card you own from outside the game or choose a face-up artifact card you own in exile. Put that card into your hand.

Flying Each player can't cast more than one spell each turn. Nonbasic lands your opponents control enter tapped.

Flash 1, Sacrifice this creature: Destroy target artifact or enchantment.

Whenever a creature you control enters, put a +1/+1 counter on each creature you control.

Flash If a nontoken creature would enter and it wasn't cast, exile it instead.

Destroy all creatures.