B-I-N-G-O

Trample
Whenever a player casts a spell, put a chip counter on its mana value.
This creature gets +9/+9 for each set of three numbers in a row with chip counters on them.

Underdome

{T}: Add {C}.
{T}: Add one mana of any color. Spend this mana only to pay Un-costs.

Mother Kangaroo

When this creature enters, roll a six-sided die. Put a number of +1/+1 counters on this creature equal to the result.

Entirely Normal Armchair

During your turn, if this card is in your hand, you may hide it on the battlefield.
{0}: Return this artifact to its owner's hand. Only your opponents may activate this ability and only if they see this artifact.
{2}, Sacrifice this artifact: Destroy target attacking creature.

Squirrel Farm

{1}{G}: Reveal a card in your hand, covering the artist credit. Target opponent guesses the artist. If they guess wrong, create a 1/1 green Squirrel creature token.

Pippa, Duchess of Dice

{2}{G}, {T}: Roll a six-sided die. It becomes a green Die creature token with power and toughness each equal to its result.
{2}{U}, {T}: Reroll any die. (Activate only any time it makes sense.)

Half-Squirrel, Half-

Whenever a nontoken creature enters,
Augment {G} ({G}, Reveal this card from your hand: Combine it with target host. Augment only as a sorcery.)

Wild Crocodile

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

Timmy, Power Gamer

{4}: You may put a creature card from your hand onto the battlefield.

Slaying Mantis

Just a second (As long as this spell is on the stack, players can't move permanents.)
This creature enters by being thrown from a distance of at least three feet.
When this creature enters, it fights each creature an opponent controls that it touched as it entered.

Forest

Spirit of the Season

When this creature 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.

Who // What // When // Where // Why

Surgeon General Commander

Whenever you augment, enchant, or mutate a creature you control, draw a card.
{T}: Add {W}, {U}, {B}, {R}, or {G}.

Free-Range Chicken

{1}{G}: Roll two six-sided dice. If both results are the same, this creature gets +X/+X until end of turn, where X is that result. If the total of those results is equal to any other total you have rolled this turn for this ability, sacrifice it. (For example, if you roll two 3s, it gets +3/+3. If you roll a 4 and a 2 for this ability later that turn, sacrifice it.)

Old Fogey

Phasing, cumulative upkeep {1}, echo {G}{G}, fading 3, bands with other Dinosaurs, protection from Homarids, snow-covered plainswalk, flanking, rampage 2

Bronze Calendar

Spells you cast cost {1} less to cast.
You must speak in a voice other than your normal voice.
When you speak in your normal voice, sacrifice this artifact.

Growth Spurt

Roll a six-sided die. Target creature gets +X/+X until end of turn, where X is the result.

Elvish Impersonators

As this creature enters, roll a six-sided die twice. Its base power becomes the first result and its base toughness becomes the second result.