Have

Pyroblast

Choose one —
• Counter target spell if it's blue.
• Destroy target permanent if it's blue.

Eldrazi Spawn

Fiery Cannonade

Fiery Cannonade deals 2 damage to each non-Pirate creature.

Utopia Sprawl

Enchant Forest
As this Aura enters, choose a color.
Whenever enchanted Forest is tapped for mana, its controller adds an additional one mana of the chosen color.

Cast into the Fire

Choose one —
• Cast into the Fire deals 1 damage to each of up to two target creatures.
• Exile target artifact.

Writhing Chrysalis

Devoid (This card has no color.)
When you cast this spell, create two 0/1 colorless Eldrazi Spawn creature tokens with "Sacrifice this token: Add {C}."
Reach
Whenever you sacrifice another Eldrazi, put a +1/+1 counter on this creature.

Generous Ent

Reach
When this creature enters, create a Food token. (It's an artifact with "{2}, {T}, Sacrifice this token: You gain 3 life.")
Forestcycling {1} ({1}, Discard this card: Search your library for a Forest card, reveal it, put it into your hand, then shuffle.)

Boarding Party

Haste
Cascade (When you cast this spell, exile cards from the top of your library until you exile a nonland card that costs less. You may cast it without paying its mana cost. Put the exiled cards on the bottom in a random order.)

The Initiative

Whenever one or more creatures a player controls deal combat damage to you, that player takes the initiative.
Whenever you take the initiative and at the beginning of your upkeep, venture into Undercity. (If you're in a dungeon, advance to the next room. If you're not, enter Undercity. You can take the initiative even if you already have it.)

Undercity

You can't enter this dungeon unless you "venture into Undercity."
Secret Entrance — Search your library for a basic land card, reveal it, put it into your hand, then shuffle. (Leads to: Forge, Lost Well)
Forge — Put two +1/+1 counters on target creature. (Leads to: Trap!, Arena)
Lost Well — Scry 2. (Leads to: Arena, Stash)
Trap! — Target player loses 5 life. (Leads to: Archives)
Arena — Goad target creature. (Leads to: Archives, Catacombs)
Stash — Create a Treasure token. (Leads to: Catacombs)
Archives — Draw a card. (Leads to: Throne of the Dead Three)
Catacombs — Create a 4/1 black Skeleton creature token with menace. (Leads to: Throne of the Dead Three)
Throne of the Dead Three — Reveal the top ten cards of your library. Put a creature card from among them onto the battlefield with three +1/+1 counters on it. It gains hexproof until your next turn. Then shuffle.

Undercity // The Initiative

Avenging Hunter

Trample
When this creature enters, you take the initiative.

Snow-Covered Mountain

Deglamer

Choose target artifact or enchantment. Its owner shuffles it into their library.

Weather the Storm

You gain 3 life.
Storm (When you cast this spell, copy it for each spell cast before it this turn.)

Arbor Elf

Malevolent Rumble

Reveal the top four cards of your library. You may put a permanent card from among them into your hand. Put the rest into your graveyard. Create a 0/1 colorless Eldrazi Spawn creature token with "Sacrifice this token: Add {C}."

Food

{2}, {T}, Sacrifice this token: You gain 3 life.

Thermokarst

Destroy target land. If that land was a snow land, you gain 1 life.

Skred

Skred deals damage to target creature equal to the number of snow permanents you control.

Mwonvuli Acid-Moss

Destroy target land. Search your library for a Forest card, put that card onto the battlefield tapped, then shuffle.

Annoyed Altisaur

Reach, trample
Cascade (When you cast this spell, exile cards from the top of your library until you exile a nonland card that costs less. You may cast it without paying its mana cost. Put the exiled cards on the bottom in a random order.)

Relic of Progenitus

{T}: Target player exiles a card from their graveyard.
{1}, Exile this artifact: Exile all graveyards. Draw a card.

Highland Forest

({T}: Add {R} or {G}.)
This land enters tapped.

Snow-Covered Forest

Wild Growth

Enchant land
Whenever enchanted land is tapped for mana, its controller adds an additional {G}.