Seed the Land

Whenever a land enters, its controller creates a 1/1 green Snake creature token.

Omnath, Locus of Rage

Landfall — Whenever a land you control enters, create a 5/5 red and green Elemental creature token.
Whenever Omnath, Locus of Rage or another Elemental you control dies, Omnath deals 3 damage to any target.

Guildless Commons

Guildless Commons enters tapped.
When Guildless Commons enters, return a land you control to its owner's hand.
{T}: Add {C}{C}.

Zendikar's Roil

Landfall — Whenever a land you control enters, create a 2/2 green Elemental creature token.

Hour of Promise

Search your library for up to two land cards, put them onto the battlefield tapped, then shuffle. Then if you control three or more Deserts, create two 2/2 black Zombie creature tokens.

Sporemound

Landfall — Whenever a land you control enters, create a 1/1 green Saproling creature token.

Rampaging Baloths

Trample
Landfall — Whenever a land you control enters, you may create a 4/4 green Beast creature token.

Gruul Turf

Gruul Turf enters tapped.
When Gruul Turf enters, return a land you control to its owner's hand.
{T}: Add {R}{G}.

Ulvenwald Hydra

Reach
Ulvenwald Hydra's power and toughness are each equal to the number of lands you control.
When Ulvenwald Hydra enters, you may search your library for a land card, put it onto the battlefield tapped, then shuffle.

Tireless Tracker

Landfall — Whenever a land you control enters, investigate. (Create a Clue token. It's an artifact with "{2}, Sacrifice this artifact: Draw a card.")
Whenever you sacrifice a Clue, put a +1/+1 counter on Tireless Tracker.

Reckless Fireweaver

Whenever an artifact you control enters, Reckless Fireweaver deals 1 damage to each opponent.

Goblin Bombardment

Sacrifice a creature: Goblin Bombardment deals 1 damage to any target.

Simic Growth Chamber

Simic Growth Chamber enters tapped.
When Simic Growth Chamber enters, return a land you control to its owner's hand.
{T}: Add {G}{U}.

Altar of the Brood

Whenever another permanent you control enters, each opponent mills a card.

Blasting Station

{T}, Sacrifice a creature: Blasting Station deals 1 damage to any target.
Whenever a creature enters, you may untap Blasting Station.

Expedition Map

{2}, {T}, Sacrifice this artifact: Search your library for a land card, reveal it, put it into your hand, then shuffle.

Ludevic, Necro-Alchemist

At the beginning of each player's end step, that player may draw a card if a player other than you lost life this turn.
Partner (You can have two commanders if both have partner.)

Toggo, Goblin Weaponsmith

Landfall — Whenever a land you control enters, create a colorless Equipment artifact token named Rock with "Equipped creature has '{1}, {T}, Sacrifice Rock: This creature deals 2 damage to any target'" and equip {1}.
Partner (You can have two commanders if both have partner.)

Impact Tremors

Whenever a creature you control enters, this enchantment deals 1 damage to each opponent.

Kodama of the East Tree

Reach
Whenever another permanent you control enters, if it wasn't put onto the battlefield with this ability, you may put a permanent card with equal or lesser mana value from your hand onto the battlefield.
Partner (You can have two commanders if both have partner.)

Wastes

Warstorm Surge

Whenever a creature you control enters, it deals damage equal to its power to any target.

Field of the Dead

Field of the Dead enters tapped.
{T}: Add {C}.
Whenever Field of the Dead or another land you control enters, if you control seven or more lands with different names, create a 2/2 black Zombie creature token.

Nesting Dragon

Flying
Landfall — Whenever a land you control enters, create a 0/2 red Dragon Egg creature token with defender and "When this creature dies, create a 2/2 red Dragon creature token with flying and '{R}: This creature gets +1/+0 until end of turn.'"

Izzet Boilerworks

Izzet Boilerworks enters tapped.
When Izzet Boilerworks enters, return a land you control to its owner's hand.
{T}: Add {U}{R}.

Terror of the Peaks

Flying
Spells your opponents cast that target Terror of the Peaks cost an additional 3 life to cast.
Whenever another creature you control enters, Terror of the Peaks deals damage equal to that creature's power to any target.

Ghirapur Aether Grid

Tap two untapped artifacts you control: Ghirapur Aether Grid deals 1 damage to any target.

Crop Rotation

As an additional cost to cast this spell, sacrifice a land.
Search your library for a land card, put that card onto the battlefield, then shuffle.

Purphoros, God of the Forge

Indestructible
As long as your devotion to red is less than five, Purphoros isn't a creature.
Whenever another creature you control enters, Purphoros deals 2 damage to each opponent.
{2}{R}: Creatures you control get +1/+0 until end of turn.

Scute Swarm

Landfall — Whenever a land you control enters, create a 1/1 green Insect creature token. If you control six or more lands, create a token that's a copy of Scute Swarm instead.

Sylvan Scrying

Search your library for a land card, reveal it, put it into your hand, then shuffle.

Pir's Whim

For each player, choose friend or foe. Each friend searches their library for a land card, puts it onto the battlefield tapped, then shuffles. Each foe sacrifices an artifact or enchantment of their choice.

Altar of Dementia

Sacrifice a creature: Target player mills cards equal to the sacrificed creature's power.