Shifting Wall

Defender (This creature can't attack.)
Shifting Wall enters with X +1/+1 counters on it.

Mob Mentality

Enchant creature
Enchanted creature has trample.
Whenever all non-Wall creatures you control attack, enchanted creature gets +X/+0 until end of turn, where X is the number of attacking creatures.

Atog

Sacrifice an artifact: Atog gets +2/+2 until end of turn.

Ornithopter

Forest

Memnite

Elvish Spirit Guide

Exile Elvish Spirit Guide from your hand: Add {G}.

Dryad Arbor

(Dryad Arbor isn't a spell, it's affected by summoning sickness, and it has "{T}: Add {G}.")

Lotus Petal

{T}, Sacrifice Lotus Petal: Add one mana of any color.

Phyrexian Marauder

Phyrexian Marauder enters with X +1/+1 counters on it.
Phyrexian Marauder can't block.
Phyrexian Marauder can't attack unless you pay {1} for each +1/+1 counter on it.

Simian Spirit Guide

Exile Simian Spirit Guide from your hand: Add {R}.

Crookshank Kobolds

Shield Sphere

Defender
Whenever Shield Sphere blocks, put a -0/-1 counter on it.

Phyrexian Walker

Glimpse of Nature

Whenever you cast a creature spell this turn, draw a card.

Reckless Charge

Target creature gets +3/+0 and gains haste until end of turn.
Flashback {2}{R} (You may cast this card from your graveyard for its flashback cost. Then exile it.)