Forgotten Ancient

Mana cost: {3}{G}
Type: Creature — Elemental
Power / toughness: 0 / 3
Set: March of the Machine Commander #297 (rare)
Price: $0.62 USD

Whenever a player casts a spell, you may put a +1/+1 counter on this creature.
At the beginning of your upkeep, you may move any number of +1/+1 counters from this creature onto other creatures.

Forgotten Ancient has 21 printings, first in Scourge (2003). EDHREC ranks it #389 among Commander cards. It appears most in Ms. Bumbleflower decks (21,089 on EDHREC). 11 public decks on TCG run it. It has 2 official rulings.

Legality

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

Public decks that run Forgotten Ancient

20 Ways to Win, led by Go-Shintai of Life's Origin
Bedecked Brokers - New Capenna Commander, led by Perrie, the Pulverizer
Breed Lethality - Commander 2016, led by Atraxa, Praetors' Voice
Breed Lethality - Commander Anthology Volume II, led by Atraxa, Praetors' Voice
Call for Backup - March of the Machine Commander, led by Bright-Palm, Soul Awakener
Counter Blitz - Final Fantasy Commander, led by Tidus, Yuna's Guardian
Peace Offering - Bloomburrow Commander, led by Ms. Bumbleflower
Quandrix Unlimited - Secrets of Strixhaven, led by Zimone, Infinite Analyst
Quantum Quandrix - Commander 2021, led by Adrix and Nev, Twincasters
Swell the Host - Commander 2015, led by Ezuri, Claw of Progress
Upgrades Unleashed - Neon Dynasty Commander, led by Chishiro, the Shattered Blade

Commanders that run Forgotten Ancient most

Deck counts from EDHREC.

Ms. Bumbleflower: 21,089 decks
Tidus, Yuna's Guardian: 15,816 decks
Animar, Soul of Elements: 12,607 decks
Helga, Skittish Seer: 11,462 decks
Kotis, the Fangkeeper: 8,901 decks
Zimone, Infinite Analyst: 8,522 decks
Wolverine, Best There Is: 7,390 decks
Skullbriar, the Walking Grave: 6,940 decks

Often played with Forgotten Ancient

Cards that show up in the same decks on EDHREC.

Rulings

2022-12-08: Forgotten Ancient's first ability will resolve before the spell that caused it to trigger. Putting a +1/+1 counter on Forgotten Ancient is optional.
2022-12-08: Forgotten Ancient's last ability doesn't target any creatures. You choose how many +1/+1 counters will be moved (and onto which creatures) as the ability resolves. Notably, once the ability starts resolving and you make these choices, no player may take actions until the ability has finished resolving.