Winding Constrictor

Mana cost: {B}{G}
Type: Creature — Snake
Power / toughness: 2 / 3
Set: Fallout #223 (uncommon)
Price: $0.43 USD

If one or more counters would be put on an artifact or creature you control, that many plus one of each of those kinds of counters are put on that permanent instead.
If you would get one or more counters, you get that many plus one of each of those kinds of counters instead.

Winding Constrictor has 6 printings, first in Aether Revolt (2017). EDHREC ranks it #2,092 among Commander cards. It appears most in The Wise Mothman decks (20,708 on EDHREC). 1 public deck on TCG runs it. It has 6 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 Winding Constrictor

Mutant Menace - Fallout, led by The Wise Mothman

Commanders that run Winding Constrictor most

Deck counts from EDHREC.

The Wise Mothman: 20,708 decks
Blech, Loafing Pest: 8,525 decks
Skullbriar, the Walking Grave: 6,355 decks
Atraxa, Praetors' Voice: 3,691 decks
Ghave, Guru of Spores: 3,262 decks
Jenova, Ancient Calamity: 2,617 decks
Tayam, Luminous Enigma: 2,288 decks
Felothar, Dawn of the Abzan: 2,097 decks

Often played with Winding Constrictor

Cards that show up in the same decks on EDHREC.

Rulings

2017-02-09: If you would get counters of multiple kinds at the same time, Winding Constrictor increases the number of each of those kinds of counters by one. The same is true if counters of multiple kinds would be placed on an artifact or creature you control.
2017-02-09: If an artifact or creature you control would enter the battlefield with a number of any kind of counters on it, it enters with that many plus one instead.
2017-02-09: If an effect includes multiple instructions to put one or more counters on an artifact or creature, such as Lifecrafter's Gift does, Winding Constrictor's effect applies to each of those instructions.
2017-02-09: Winding Constrictor's effect can't apply to itself as it's entering the battlefield or to any other permanent entering the battlefield at the same time as it.
2017-02-09: If you control two Winding Constrictors, the number of counters placed on the artifact or creature is the original number plus two. Three Winding Constrictors adds three to the original number, and so on.
2017-09-29: If a nonartifact, noncreature permanent (such as a planeswalker) would enter the battlefield with counters on it and become an artifact or a creature on the battlefield due to another card's effect (such as that of Mycosynth Lattice), Winding Constrictor's effect will give that permanent another of those counters.