Emcee

Whenever another creature enters, you may stand up and say in a deep, booming voice, "Presenting . . . " and that creature's name. If you do, put a +1/+1 counter on that creature.

Gus enters with a +1/+1 counter on it for each Magic game you have lost to one of your opponents since you last won a game against them.

Fascist Art Director

{W}{W}: Fascist Art Director gains protection from the artist of your choice until end of turn.

Kudo, King Among Bears

Other creatures have base power and toughness 2/2 and are Bears in addition to their other types.

Spirit of the Season

When Spirit of the Season enters, it gains haste if it's summer. Put a +1/+1 counter on it if it's autumn. You gain 5 life if it's winter. If it's spring, search your library for a basic land card, reveal it, put it into your hand, then shuffle.

Our Market Research Shows That Players Like Really Long Card Names So We Made this Card to Have the Absolute Longest Card Name Ever Elemental

Art rampage 2 (Whenever this creature becomes blocked by a creature, it gets +2/+2 for each creature in the blocker's art beyond the first.)

Squirrel Dealer

When Squirrel Dealer enters, ask a person outside the game "Do you like Squirrels?" If they do, create a 1/1 green Squirrel creature token.

Steel Squirrel

Whenever you roll a 5 or higher on a die, Steel Squirrel gets +X/+X until end of turn, where X is the result.
{6}: Roll a six-sided die.

Knight of the Kitchen Sink

First strike, protection from black borders (Nothing with a black border can block, target, deal damage to, or attach to this creature.)

Man of Measure

As long as you're shorter than an opponent, Man of Measure gets +0/+1 and has first strike.
As long as you're taller than an opponent, Man of Measure gets +1/+0.

Willing Test Subject

Reach
Whenever you roll a 4 or higher on a die, put a +1/+1 counter on Willing Test Subject.
{6}: Roll a six-sided die.

Jackknight

Whenever another artifact you control enters, put a +1/+1 counter on Jackknight. If that artifact is a Contraption, Jackknight gains lifelink until end of turn.

Border Guardian

Whenever you cast a silver-bordered spell, put a +1/+1 counter on Border Guardian.
Whenever you cast a black-bordered spell, Border Guardian can't be blocked this turn.
Whenever you cast a white-bordered spell, Border Guardian gains double strike until end of turn.

Tchotchke Elemental

Whenever you create a token or put a counter or a sticker on another permanent, put a knickknack counter on Tchotchke Elemental. Use a unique item that completely fits on Tchotchke Elemental for each knickknack counter.
Tchotchke Elemental gets +1/+1 for each knickknack counter on it.

Clay Pigeon

Flying
{1}, Throw Clay Pigeon into the air at least two feet above your head while seated: If you catch Clay Pigeon with one hand, prevent all damage a source of your choice would deal to you this turn and tap Clay Pigeon. Otherwise, sacrifice it.

Knight in _____ Armor

First strike
As this creature enters, you may put a name sticker on it.
This creature has protection from names that start with the same letter as a name sticker on it.

First strike, protection from two-word names (Nothing with exactly two words in its name can block, target, deal damage to, or attach to this creature. Hyphenated words are one word.)

Ground Pounder

{3}{G}: Roll a six-sided die. Ground Pounder gets +X/+X until end of turn, where X is the result.
Whenever you roll a 5 or higher on a die, Ground Pounder gains trample until end of turn.

Mesa Chicken

Stand up, Flap your arms, Cluck like a chicken: Mesa Chicken gains flying until end of turn.

B-I-N-G-O

Trample
Whenever a player casts a spell, put a chip counter on its mana value.
B-I-N-G-O gets +9/+9 for each set of three numbers in a row with chip counters on them.

T.A.P.P.E.R.

{T}, Tap an untapped creature you control that has a hat: Tap target creature.

Icing Manipulator

Each +1/+1 counter on a creature you control is also a Food token. (It's an artifact with "{2}, {T}, Sacrifice this artifact: You gain 3 life.")
{3}{G}, {T}: Roll two six-sided dice. For each odd result, put a +1/+1 counter on a creature of your choice. Activate only as a sorcery.

Jermane, Pride of the Circus

{G}, {T}: Put two +1/+1 counters on target creature with four or more legs.
{1}{G}{G}, {T}: Until end of turn, all creatures able to block target creature with four or more legs do so.

Hydradoodle

As Hydradoodle enters, roll X six-sided dice. Hydradoodle enters with a number of +1/+1 counters on it equal to the total of those results.
Reach, trample