Whenever Cephalid Illusionist becomes the target of a spell or ability, mill three cards. {2}{U}, {T}: Prevent all combat damage that would be dealt to and dealt by target creature you control this turn.
Threshold — As long as seven or more cards are in your graveyard, Cephalid Sage has "When Cephalid Sage enters, draw three cards, then discard two cards."
When Llawan, Cephalid Empress enters, return all blue creatures your opponents control to their owners' hands. Your opponents can't cast blue creature spells.
Flying Threshold — As long as seven or more cards are in your graveyard, Possessed Aven gets +1/+1, is black, and has "{2}{B}, {T}: Destroy target blue creature."
Flying Threshold — As long as seven or more cards are in your graveyard, Boneshard Slasher gets +2/+2 and has "When Boneshard Slasher becomes the target of a spell or ability, sacrifice it."