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.

Spelling Bee

Flying, deathtouch
Whenever Spelling Bee deals combat damage to a player, that player looks at the top card of your library and chooses a word on that card. You spell that word. If you spell it correctly, draw a card. Otherwise, scry 1.

Giggling Skitterspike

Indestructible
Whenever Giggling Skitterspike attacks, blocks, or becomes the target of a spell, it deals damage equal to its power to each opponent.
{5}: Monstrosity 5. (If this creature isn't monstrous, put five +1/+1 counters on it and it becomes monstrous.)

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

Wild Crocodile

When this creature enters, search your library for a basic land card, reveal it, put it into your hand, then shuffle.

Rock Lobster

Creatures named Scissors Lizard can't attack or block.

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.

Scissors Lizard

Creatures named Paper Tiger can't attack or block.

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.

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.

Earl of Squirrel

Squirrellink (Damage dealt by this creature also causes you to create that many 1/1 green Squirrel creature tokens.)
Creature tokens you control are Squirrels in addition to their other creature types.
Other Squirrels you control get +1/+1.

Paper Tiger

Creatures named Rock Lobster can't attack or block.

Centaur of Attention

When Centaur of Attention enters, roll five six-sided dice and store those results on it.
At the beginning of combat on your turn, you may reroll any number of Centaur of Attention's stored results.
Centaur of Attention gets +X/+X, where X is the greatest number of stored results on it of the same value.