Obuun, Mul Daya Ancestor

At the beginning of combat on your turn, up to one target land you control becomes an X/X Elemental creature with trample and haste until end of turn, where X is Obuun's power. It's still a land.
Landfall — Whenever a land you control enters, put a +1/+1 counter on target creature.

Arcane Signet

{T}: Add one mana of any color in your commander's color identity.

Active Volcano

Choose one —
• Destroy target blue permanent.
• Return target Island to its owner's hand.

Savageborn Hydra

Double strike
Savageborn Hydra enters with X +1/+1 counters on it.
{1}{R/G}: Put a +1/+1 counter on Savageborn Hydra. Activate only as a sorcery.

Adamant Will

Target creature gets +2/+2 and gains indestructible until end of turn. (Damage and effects that say "destroy" don't destroy it.)

Abrade

Choose one —
• Abrade deals 3 damage to target creature.
• Destroy target artifact.

Abolish

You may discard a Plains card rather than pay this spell's mana cost.
Destroy target artifact or enchantment.

Ulasht, the Hate Seed

Ulasht, the Hate Seed enters with a +1/+1 counter on it for each other red creature you control and a +1/+1 counter on it for each other green creature you control.
{1}, Remove a +1/+1 counter from Ulasht: Choose one —
• Ulasht deals 1 damage to target creature.
• Create a 1/1 green Saproling creature token.

Sol Ring

Aeronaut's Wings

Equipped creature gets +1/+0 and has flying.
Equip {2} ({2}: Attach to target creature you control. Equip only as a sorcery.)