Counter target spell unless its controller pays {2}. Look at its controller's hand and the top card of their library.

Flying
Equipped creature gets +2/+0.
Equip {2}
Spellcharge 2

{3}{G}{G}, Exile Release the Unchained Melody from your hand: At the beginning of your next upkeep, you may cast Release the Unchained Melody from exile without paying its mana cost. Activate only as a sorcery.
Create three 3/3 green Elemental Spirit creature tokens.

Relentless Busker can't block.
{VP}{VP}{VP}: Return Relentless Busker from your graveyard to the battlefield.

Choose two —
• Target player may scry 3.
• Return target permanent you control to its owner's hand.
• You may tap or untap target creature.

Other creatures you control get +1/+1 and have vigilance.
Spellcharge 5

When Remnant of Zakros enters, choose one —
• Each player sacrifices a creature.
• Each player sacrifices an enchantment.

Replicated Regiment enters with a +1/+1 counter and a vigilance counter on it.
At the beginning of your upkeep, you may move a counter from Replicated Regiment onto another creature.

Reach
Replicrawler gets +1/+1 for each other artifact creature you control.
If you would create a token, you may pay {B}. If you do, create a token that's a copy of Replicrawler instead.

Target creature you control gets +1/+0 and gains haste until end of turn.
Draw a card.

Drop — Reptilian Raver enters with two +1/+1 counters on it if you didn't cast any creature spells during your last turn.

Counter target spell with mana value X. If that spell is targeting you or a creature you control, you may choose new targets for it instead.

When Research Grant enters, look at the top three cards of your library. Put one into your hand and the rest into your graveyard.
You've cast two or more spells this turn.
You've drawn two or more cards this turn.

Gain control of target creature until end of turn. Untap that creature. It gains haste until end of turn. If you control another permanent you don't own, it gets +2/+0 until end of turn.

At the beginning of combat on your turn, you may pay {1}. If you do, create a 1/1 red and green Elemental creature token. It gains haste. Sacrifice it at end of combat.

When Resourceful Hireling enters, choose one —
• Create a 0/0 colorless Robot artifact creature token with a +1/+1 counter on it.
• Create a Treasure token.

{T}: Add {C}.
Whenever Resting Place attacks, sacrifice it at end of combat.
Spellcharge 5

This spell has lifelink as long as you control a creature with lifelink.
Retaliatory Outburst deals 4 damage to target tapped creature.

When Retrofit Paladin enters, tap up to two target creatures with power 3 or less.

Defender
As long as you control a creature with power 4 or greater, Revel Watchguard can attack as though it didn't have defender.

Flying
Drop — When Revenant Benefactor enters, if you didn't cast any creature spells during your last turn, return target creature card from your graveyard to the battlefield.

Return target creature card with mana value 4 or less from your graveyard to the battlefield. It gets +2/+1 and gains trample and haste until end of turn. Sacrifice it at the beginning of the next end step.

Exile target artifact or enchantment.

Revolutionary Redistributer enters with three +1/+1 counters on it.
At the beginning of combat on your turn, you may move a counter from a permanent you control to a second permanent you control.

When Revolutionary Supplier enters, you may search your library for a card named Explosive Canister and/or a card named Fencer's Foil, reveal them, put them into your hand, then shuffle.
The first artifact spell you cast each turn costs {1} less to cast.