Tendo Ice Bridge

This land enters with a charge counter on it.
{T}: Add {C}.
{T}, Remove a charge counter from this land: Add one mana of any color.

Great Divide Guide

Each land and Ally you control has "{T}: Add one mana of any color."

Tolaria West

This land enters tapped.
{T}: Add {U}.
Transmute {1}{U}{U} ({1}{U}{U}, Discard this card: Search your library for a card with mana value 0, reveal it, put it into your hand, then shuffle. Transmute only as a sorcery.)

Shimmerwilds Growth

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

Kederekt Leviathan

When this creature enters, return all other nonland permanents to their owners' hands.
Unearth {6}{U} ({6}{U}: Return this card from your graveyard to the battlefield. It gains haste. Exile it at the beginning of the next end step or if it would leave the battlefield. Unearth only as a sorcery.)

Twitching Doll

{T}: Add one mana of any color. Put a nest counter on this creature.
{T}, Sacrifice this creature: Create a 2/2 green Spider creature token with reach for each counter on this creature. Activate only as a sorcery.

Animal Attendant

{T}: Add one mana of any color. If that mana is spent to cast a non-Human creature spell, that creature enters with an additional +1/+1 counter on it.