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.

Containment Priest

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

Pest Control

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