Megalith Eidolon

Flying
Nightfall: Megalith Eidolon gains +1/+1 and
"{b}: Megalith Eidolon gains +1/+1 until end
of turn." (Nightfall, triggers the first time a Swamp
or mono-Black creature enters the battlefield under
your control.)
"The Monoliths of the Magalos Labrynthe are
always guarded by dark shadows. Yet they are
cowards that strike only when they have the
advantage of darkness' might to call upon. "
- Stessan Spekunker