Three Steps Ahead

Spree (Choose one or more additional costs.)
+ {1}{U} — Counter target spell.
+ {3} — Create a token that's a copy of target artifact or creature you control.
+ {2} — Draw two cards, then discard a card.

Hallowed Fountain

({T}: Add {W} or {U}.)
As Hallowed Fountain enters, you may pay 2 life. If you don't, it enters tapped.

Sundown Pass

Sundown Pass enters tapped unless you control two or more other lands.
{T}: Add {R} or {W}.

Faithful Mending

You gain 2 life, draw two cards, then discard two cards.
Flashback {1}{W}{U} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Spell Pierce

Counter target noncreature spell unless its controller pays {2}.

Spirebluff Canal

Spirebluff Canal enters tapped unless you control two or fewer other lands.
{T}: Add {U} or {R}.

Steam Vents

({T}: Add {U} or {R}.)
As Steam Vents enters, you may pay 2 life. If you don't, it enters tapped.

Rakdos Joins Up

When Rakdos Joins Up enters, return target creature card from your graveyard to the battlefield with two additional +1/+1 counters on it.
Whenever a legendary creature you control dies, Rakdos Joins Up deals damage equal to that creature's power to target opponent.

Otherworldly Gaze

Surveil 3. (Look at the top three cards of your library, then put any number of them into your graveyard and the rest on top of your library in any order.)
Flashback {1}{U} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Hulking Metamorph

Prototype {2}{U}{U} — 3/3 (You may cast this spell with different mana cost, color, and size. It keeps its abilities and types.)
You may have Hulking Metamorph enter as a copy of an artifact or creature you control, except it's an artifact creature in addition to its other types, and its power and toughness are equal to Hulking Metamorph's power and toughness.

No More Lies

Counter target spell unless its controller pays {3}. If that spell is countered this way, exile it instead of putting it into its owner's graveyard.

Izzet Charm

Choose one —
• Counter target noncreature spell unless its controller pays {2}.
• Izzet Charm deals 2 damage to target creature.
• Draw two cards, then discard two cards.

Abuelo's Awakening

Return target artifact or non-Aura enchantment card from your graveyard to the battlefield with X additional +1/+1 counters on it. It's a 1/1 Spirit creature with flying in addition to its other types.

Seachrome Coast

Seachrome Coast enters tapped unless you control two or fewer other lands.
{T}: Add {W} or {U}.

Sacred Foundry

({T}: Add {R} or {W}.)
As Sacred Foundry enters, you may pay 2 life. If you don't, it enters tapped.