Sol Ring

Vhati il-Dal

{T}: Until end of turn, target creature has base power 1 or base toughness 1.

Doran, the Siege Tower

Each creature assigns combat damage equal to its toughness rather than its power.

Maha, Its Feathers Night

Flying, trample
Ward—Discard a card.
Creatures your opponents control have base toughness 1.

Sandsteppe Citadel

This land enters tapped.
{T}: Add {W}, {B}, or {G}.

Arcane Signet

{T}: Add one mana of any color in your commander's color identity.

Command Tower

Overwhelming Splendor

Enchant player
Creatures enchanted player controls lose all abilities and have base power and toughness 1/1.
Enchanted player can't activate abilities that aren't mana abilities or loyalty abilities.