Mob Justice

Mob Justice deals damage to target player or planeswalker equal to the number of creatures you control.

Halo Hopper

Convoke (Your creatures can help cast this spell. Each creature you tap while casting this spell pays for {1} or one mana of that creature's color.)

Simian Spirit Guide

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

Kobolds of Kher Keep

Lotus Petal

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

Ornithopter

Might of the Masses

Target creature gets +1/+1 until end of turn for each creature you control.

Forest

Wooded Ridgeline

({T}: Add {R} or {G}.)
Wooded Ridgeline enters tapped.

Crookshank Kobolds

Crimson Kobolds

Goblin Bushwhacker

Kicker {R} (You may pay an additional {R} as you cast this spell.)
When this creature enters, if it was kicked, creatures you control get +1/+0 and gain haste until end of turn.

Will-Forged Golem

Manamorphose

Add two mana in any combination of colors.
Draw a card.

Lightning Bolt

Lightning Bolt deals 3 damage to any target.

Land Grant

If you have no land cards in hand, you may reveal your hand rather than pay this spell's mana cost.
Search your library for a Forest card, reveal that card, put it into your hand, then shuffle.