Aerith, All Is One

Aerith is an artifact in addition to it's other types. Unless you control one other artifact, enchantment and creature, Aerith can't attack or block.

Ward - Sacrifice an Artifact or Enchantment

{t} If you cast a Creature spell this turn, draw a card. If you cast an Artifact spell this turn, gain 1 life. If you cast an Enchantment spell this turn, you may put a land from your hand onto the battlefield.