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.

When Renowned Roughrider enters or leaves the battlefield, create a 1/1 white Human creature token. Then if you control four or more creatures, put a +1/+1 counter on a creature you control.
Wander {4}{W}{W}

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.

Target opponent discards their hand, then draws seven cards. You discard your hand, then exile the top seven cards of that player's library. You may play those cards as long as they remain exiled, and mana of any type can be spent to cast them.

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.

Choose one —
• Destroy target artifact.
• Destroy target enchantment.
• Exile target card from a graveyard.

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.