Plains

Arcane Sanctum

This land enters tapped.
{T}: Add {W}, {U}, or {B}.

Island

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 this creature 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 this creature's power and toughness.

Nomad Outpost

This land enters tapped.
{T}: Add {R}, {W}, or {B}.

Mountain

Founding the Third Path

Read ahead (Choose a chapter and start with that many lore counters. Add one after your draw step. Skipped chapters don't trigger. Sacrifice after III.)
I — You may cast an instant or sorcery spell with mana value 1 or 2 from your hand without paying its mana cost.
II — Target player mills four cards.
III — Exile target instant or sorcery card from your graveyard. Copy it. You may cast the copy.

Fallaji Archaeologist

When this creature enters, mill three cards. You may put a noncreature, nonland card from among the cards milled this way into your hand. If you don't, put a +1/+1 counter on this creature. (To mill a card, put the top card of your library into your graveyard.)

Crumbling Necropolis

This land enters tapped.
{T}: Add {U}, {B}, or {R}.

Swamp

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.

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.

Sharuum the Hegemon

Flying
When Sharuum enters, you may return target artifact card from your graveyard to the battlefield.

Thrilling Discovery

You gain 2 life. Then you may discard two cards. If you do, draw three cards.

Mystic Monastery

This land enters tapped.
{T}: Add {U}, {R}, or {W}.

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.

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.)

Tainted Indulgence

Draw two cards. Then discard a card unless there are five or more mana values among cards in your graveyard.