Jared Carthalion

+1: Create a 3/3 Kavu creature token with trample that's all colors.
−3: Choose up to two target creatures. For each of them, put a number of +1/+1 counters on it equal to the number of colors it is.
−6: Return target multicolored card from your graveyard to your hand. If that card was all colors, draw a card and create two Treasure tokens.
Jared Carthalion can be your commander.

Exploding Borders

Domain — Search your library for a basic land card, put that card onto the battlefield tapped, then shuffle. Exploding Borders deals X damage to target player or planeswalker, where X is the number of basic land types among lands you control.

Might of Alara

Domain — Target creature gets +1/+1 until end of turn for each basic land type among lands you control.

Radha, Coalition Warlord

Domain — Whenever Radha becomes tapped, another target creature you control gets +X/+X until end of turn, where X is the number of basic land types among lands you control.

Worldly Counsel

Domain — Look at the top X cards of your library, where X is the number of basic land types among lands you control. Put one of those cards into your hand and the rest on the bottom of your library in any order.

Collective Restraint

Domain — Creatures can't attack you unless their controller pays {X} for each creature they control that's attacking you, where X is the number of basic land types among lands you control.

Tromp the Domains

Domain — Until end of turn, creatures you control gain trample and get +1/+1 for each basic land type among lands you control.

Draco

Domain — This spell costs {2} less to cast for each basic land type among lands you control.
Flying
Domain — At the beginning of your upkeep, sacrifice this creature unless you pay {10}. This cost is reduced by {2} for each basic land type among lands you control.

Shadow Prophecy

Domain — Look at the top X cards of your library, where X is the number of basic land types among lands you control. Put up to two of them into your hand and the rest into your graveyard. You lose 2 life.

Allied Strategies

Domain — Target player draws a card for each basic land type among lands they control.

Leyline Binding

Flash
Domain — This spell costs {1} less to cast for each basic land type among lands you control.
When this enchantment enters, exile target nonland permanent an opponent controls until this enchantment leaves the battlefield.

Scion of Draco

Domain — This spell costs {2} less to cast for each basic land type among lands you control.
Flying
Each creature you control has vigilance if it's white, hexproof if it's blue, lifelink if it's black, first strike if it's red, and trample if it's green.

Evasive Action

Domain — Counter target spell unless its controller pays {1} for each basic land type among lands you control.

Sphinx of Clear Skies

Flying, ward {2}
Domain — Whenever this creature deals combat damage to a player, reveal the top X cards of your library, where X is the number of basic land types among lands you control. An opponent separates those cards into two piles. Put one pile into your hand and the other into your graveyard. (Piles can be empty.)

Briar Hydra

Trample
Domain — Whenever this creature deals combat damage to a player, put X +1/+1 counters on target creature you control, where X is the number of basic land types among lands you control.

Artillery Blast

Domain — Artillery Blast deals X damage to target tapped creature, where X is 1 plus the number of basic land types among lands you control.

Magnigoth Treefolk

Domain — For each basic land type among lands you control, this creature has landwalk of that type. (It can't be blocked as long as defending player controls a land of that type.)

Jodah's Codex

Domain — {5}, {T}: Draw a card. This ability costs {1} less to activate for each basic land type among lands you control.

Gaea's Might

Bortuk Bonerattle

Domain — When Bortuk Bonerattle enters, if you cast it, choose target creature card in your graveyard. Return that card to the battlefield if its mana value is less than or equal to the number of basic land types among lands you control. Otherwise, put it into your hand.

Drag to the Bottom

Domain — Each creature gets -X/-X until end of turn, where X is 1 plus the number of basic land types among lands you control.

Zar Ojanen, Scion of Efrava

Domain — Whenever Zar Ojanen becomes tapped, put a +1/+1 counter on each creature you control with toughness less than the number of basic land types among lands you control.

Exotic Curse

Enchant creature
Domain — Enchanted creature gets -1/-1 for each basic land type among lands you control.

Slimefoot's Survey

Domain — Search your library for up to two land cards that each have a basic land type, put them onto the battlefield tapped, then shuffle. Look at the top X cards of your library, where X is the number of basic land types among lands you control. Put up to one of them on top of your library and the rest on the bottom of your library in a random order.

Manaforce Mace

Domain — Equipped creature gets +1/+1 for each basic land type among lands you control.
Equip {3}

Aven Trailblazer

Flying
Domain — Aven Trailblazer's toughness is equal to the number of basic land types among lands you control.

Herd Migration

Domain — Create a 3/3 green Beast creature token for each basic land type among lands you control.
{1}{G}, Discard this card: Search your library for a basic land card, reveal it, put it into your hand, then shuffle. You gain 3 life.

Nael, Avizoa Aeronaut

Flying
Domain — Whenever Nael deals combat damage to a player, look at the top X cards of your library, where X is the number of basic land types among lands you control. Put up to one of them on top of your library and the rest on the bottom in a random order. Then if there are five basic land types among lands you control, draw a card.

Voda Sea Scavenger

Domain — When this creature enters, look at the top X cards of your library, where X is the number of basic land types among lands you control. You may put one of those cards on top of your library. Put the rest on the bottom of your library in a random order.

Prismatic Geoscope

This artifact enters tapped.
Domain — {T}: Add X mana in any combination of colors, where X is the number of basic land types among lands you control.