Faithless Looting

Draw two cards, then discard two cards.
Flashback {2}{R} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Rouse the Mob

Strive — This spell costs {2}{R} more to cast for each target beyond the first.
Any number of target creatures each get +2/+0 and gain trample until end of turn.

Wild Ride

Target creature gets +3/+0 and gains haste until end of turn.
Harmonize {4}{R} (You may cast this card from your graveyard for its harmonize cost. You may tap a creature you control to reduce that cost by {X}, where X is its power. Then exile this spell.)

Mishra's Bauble

{T}, Sacrifice this artifact: Look at the top card of target player's library. Draw a card at the beginning of the next turn's upkeep.

Slickshot Show-Off

Flying, haste
Whenever you cast a noncreature spell, this creature gets +2/+0 until end of turn.
Plot {1}{R} (You may pay {1}{R} and exile this card from your hand. Cast it as a sorcery on a later turn without paying its mana cost. Plot only as a sorcery.)

Monastery Swiftspear

Haste
Prowess (Whenever you cast a noncreature spell, this creature gets +1/+1 until end of turn.)

Mountain

Leyline of Resonance

If this card is in your opening hand, you may begin the game with it on the battlefield.
Whenever you cast an instant or sorcery spell that targets only a single creature you control, copy that spell. You may choose new targets for the copy.