Tremble

Each player sacrifices a land of their choice.

Forest

Reach
{T}, Tap an untapped creature you control: Add one mana of any color.

Each player sacrifices a permanent of their choice.

Whenever another creature enters, untap Midnight Guard.

Defender
{T}, Tap an untapped creature you control: Add one mana of any color.

Gathered Swarm — Whenever one or more tokens you control enter, put a +1/+1 counter on Cloakwood Swarmkeeper.

Sacrifice a token: Glimmer Bairn gets +2/+2 until end of turn.

Return a Forest you control to its owner's hand: Untap target creature. Activate only once each turn.

As an additional cost to cast this spell, sacrifice a land.
Destroy target land.

Whenever Stonybrook Schoolmaster becomes tapped, you may create a 1/1 blue Merfolk Wizard creature token.

{T}, Tap an untapped artifact or creature you control: Add one mana of any color.

When Akki Blizzard-Herder dies, each player sacrifices a land of their choice.

{T}, Tap an untapped creature you control: Add one mana of any color.

Nettle Sentinel doesn't untap during your untap step.
Whenever you cast a green spell, you may untap Nettle Sentinel.