Containment Priest

Flash
If a nontoken creature would enter and it wasn't cast, exile it instead.

Lavinia, Azorius Renegade

Each opponent can't cast noncreature spells with mana value greater than the number of lands that player controls.
Whenever an opponent casts a spell, if no mana was spent to cast it, counter that spell.

Final Showdown

Spree (Choose one or more additional costs.)
+ {1} — All creatures lose all abilities until end of turn.
+ {1} — Choose a creature you control. It gains indestructible until end of turn.
+ {3}{W}{W} — Destroy all creatures.

Pest Control

Destroy all nonland permanents with mana value 1 or less.
Cycling {2} ({2}, Discard this card: Draw a card.)