Deep Gnome Terramancer

Flash
Mold Earth — Whenever one or more lands enter under an opponent's control without being played, you may search your library for a Plains card, put it onto the battlefield tapped, then shuffle. Do this only once each turn.

Academy Rector

When this creature dies, you may exile it. If you do, search your library for an enchantment card, put that card onto the battlefield, then shuffle.

Esper Sentinel

Whenever an opponent casts their first noncreature spell each turn, draw a card unless that player pays {X}, where X is this creature's power.

Giver of Runes

{T}: Another target creature you control gains protection from colorless or from the color of your choice until end of turn.

Archivist of Oghma

Flash
Whenever an opponent searches their library, you gain 1 life and draw a card.

Ao, the Dawn Sky

Flying, vigilance
When Ao dies, choose one —
• Look at the top seven cards of your library. Put any number of nonland permanent cards with total mana value 4 or less from among them onto the battlefield. Put the rest on the bottom of your library in a random order.
• Put two +1/+1 counters on each permanent you control that's a creature or Vehicle.