Flying Whenever another Spirit you control enters, Mausoleum Wanderer gets +1/+1 until end of turn. Sacrifice Mausoleum Wanderer: Counter target instant or sorcery spell unless its controller pays {X}, where X is Mausoleum Wanderer's power.
Flying Whenever you cast an instant or sorcery spell, Mercurial Geists gets +3/+0 until end of turn.
"Procedural misstep: provocation of geists for the purpose of yielding more energy can compromise containment units. Next action: clean up mess." —Laboratory notes
Put two +1/+1 counters on target creature. Delirium — Put three +1/+1 counters on that creature instead if there are four or more card types among cards in your graveyard.
Mikaeus, the Lunarch enters with X +1/+1 counters on it. {T}: Put a +1/+1 counter on Mikaeus. {T}, Remove a +1/+1 counter from Mikaeus: Put a +1/+1 counter on each other creature you control.
Whenever an opponent casts their first spell each turn, that player exiles the top card of their library. If it's a nonland card, you may cast it without paying its mana cost.
Infinite wisdom cannot be contained within a single mind.