Nykthos, Shrine to Nyx

{T}: Add {C}.
{2}, {T}: Choose a color. Add an amount of mana of that color equal to your devotion to that color. (Your devotion to a color is the number of mana symbols of that color in the mana costs of permanents you control.)

Plains

Esper Sentinel

Whenever an opponent casts their first noncreature spell each turn, draw a card unless that player pays {X}, where X is Esper Sentinel's power.

Stasis Snare

Flash (You may cast this spell any time you could cast an instant.)
When Stasis Snare enters, exile target creature an opponent controls until Stasis Snare leaves the battlefield. (That creature returns under its owner's control.)

Flickerwisp

Flying
When Flickerwisp enters, exile another target permanent. Return that card to the battlefield under its owner's control at the beginning of the next end step.

Soul Warden

Whenever another creature enters, you gain 1 life.

Elesh Norn, Grand Cenobite

Vigilance
Other creatures you control get +2/+2.
Creatures your opponents control get -2/-2.

Springjack Shepherd

Chroma — When Springjack Shepherd enters, create a 0/1 white Goat creature token for each white mana symbol in the mana costs of permanents you control.

Knight of the White Orchid

First strike
When Knight of the White Orchid enters, if an opponent controls more lands than you, you may search your library for a Plains card, put it onto the battlefield, then shuffle.

Mirrorweave

Each other creature becomes a copy of target nonlegendary creature until end of turn.

Thistledown Liege

Flash
Other white creatures you control get +1/+1.
Other blue creatures you control get +1/+1.