Peer Pressure

Choose a creature type. If you control more creatures of that type than each other player, you gain control of all creatures of that type. (This effect lasts indefinitely.)

Amoeboid Changeling

Changeling (This card is every creature type.)
{T}: Target creature gains all creature types until end of turn.
{T}: Target creature loses all creature types until end of turn.

Spark Double

You may have Spark Double enter as a copy of a creature or planeswalker you control, except it enters with an additional +1/+1 counter on it if it's a creature, it enters with an additional loyalty counter on it if it's a planeswalker, and it isn't legendary.

Artificial Evolution

Change the text of target spell or permanent by replacing all instances of one creature type with another. The new creature type can't be Wall. (This effect lasts indefinitely.)

Unnatural Selection

{1}: Choose a creature type other than Wall. Target creature becomes that type until end of turn.

Mistform Mutant

{1}{U}: Choose a creature type other than Wall. Target creature becomes that type until end of turn.

Elemental Bond

Whenever a creature you control with power 3 or greater enters, draw a card.

Standardize

Choose a creature type other than Wall. Each creature becomes that type until end of turn.

Hunted Phantasm

Hunted Phantasm can't be blocked.
When Hunted Phantasm enters, target opponent creates five 1/1 red Goblin creature tokens.

Imagecrafter

{T}: Choose a creature type other than Wall. Target creature becomes that type until end of turn.