Nykthos, Shrine to Nyx

Type: Legendary Land
Set: The List #THS-223 (rare)
Price: $56.85 USD

{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.)

Nykthos, Shrine to Nyx has 4 printings, first in Theros (2013). EDHREC ranks it #163 among Commander cards. It appears most in Giada, Font of Hope decks (16,994 on EDHREC). 1 public deck on TCG runs it. It has 5 official rulings.

Legality

commander: legal
legacy: legal
vintage: legal
pauper: not legal
modern: legal
pioneer: legal
standard: not legal
brawl: legal

Public decks that run Nykthos, Shrine to Nyx

Angels: They're Just Like Us, but Cooler and with Wings - Secret Lair Drop, led by Bruna, the Fading Light

Commanders that run Nykthos, Shrine to Nyx most

Deck counts from EDHREC.

Giada, Font of Hope: 16,994 decks
Sephiroth, Fabled SOLDIER // Sephiroth, One-Winged Angel: 11,187 decks
K'rrik, Son of Yawgmoth: 9,202 decks
Krenko, Mob Boss: 9,081 decks
Anti-Venom, Horrifying Healer: 5,601 decks
Tergrid, God of Fright // Tergrid's Lantern: 4,557 decks
Sheoldred, the Apocalypse: 4,510 decks
Clive, Ifrit's Dominant // Ifrit, Warden of Inferno: 4,374 decks

Often played with Nykthos, Shrine to Nyx

Cards that show up in the same decks on EDHREC.

Rulings

2013-09-15: The second ability is a mana ability. It doesn't use the stack and can't be responded to.
2013-09-15: Hybrid mana symbols, monocolored hybrid mana symbols, and Phyrexian mana symbols do count toward your devotion to their color(s).
2013-09-15: If an activated ability or triggered ability has an effect that depends on your devotion to a color, you count the number of mana symbols of that color among the mana costs of permanents you control as the ability resolves. The permanent with that ability will be counted if it's still on the battlefield at that time.
2013-09-15: Numeric mana symbols ({0}, {1}, and so on) in mana costs of permanents you control don't count toward your devotion to any color.
2013-09-15: Mana symbols in the text boxes of permanents you control don't count toward your devotion to any color.