Rigo, Streetwise Mentor

Rigo, Streetwise Mentor enters with a shield counter on it. (If it would be dealt damage or destroyed, remove a shield counter from it instead.)
Whenever you attack a player or planeswalker with one or more creatures with power 1 or less, draw a card.

Siren Stormtamer

Flying
{U}, Sacrifice Siren Stormtamer: Counter target spell or ability that targets you or a creature you control.

Tetsuko Umezawa, Fugitive

Creatures you control with power or toughness 1 or less can't be blocked.

Judge's Familiar

Flying
Sacrifice Judge's Familiar: Counter target instant or sorcery spell unless its controller pays {1}.

Arcane Signet

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

Edric, Spymaster of Trest

Whenever a creature deals combat damage to one of your opponents, its controller may draw a card.

Patch Up

Return up to three target creature cards with total mana value 3 or less from your graveyard to the battlefield.

Slither Blade

Sol Ring

Mirror Entity

Changeling (This card is every creature type.)
{X}: Until end of turn, creatures you control have base power and toughness X/X and gain all creature types.

Druids' Repository

Whenever a creature you control attacks, put a charge counter on Druids' Repository.
Remove a charge counter from Druids' Repository: Add one mana of any color.