Echo Storm

Mana cost: {3}{U}{U}
Type: Sorcery
Set: Treasure Chest #70695 (rare)

When you cast this spell, copy it for each time you've cast your commander from the command zone this game. You may choose new targets for the copies.
Create a token that's a copy of target artifact.

Echo Storm has 3 printings, first in Commander 2018 (2018). EDHREC ranks it #11,857 among Commander cards. It appears most in Gimbal, Gremlin Prodigy decks (907 on EDHREC). 2 public decks on TCG run it. It has 11 official rulings.

Legality

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

Public decks that run Echo Storm

Exquisite Invention - Commander 2018, led by Saheeli, the Gifted
Tinker Time - March of the Machine Commander, led by Gimbal, Gremlin Prodigy

Commanders that run Echo Storm most

Deck counts from EDHREC.

Often played with Echo Storm

Cards that show up in the same decks on EDHREC.

Rulings

2018-07-13: If the copied artifact is copying something else (for example, if the copied artifact is a Sculpting Steel), then the token enters the battlefield as whatever that artifact copied.
2018-07-13: The token copies exactly what was printed on the original artifact and nothing else (unless that artifact is copying something else or is a token; see below). It doesn't copy whether that artifact is tapped or untapped, whether it has any counters on it or Auras attached to it, or any non-copy effects that have changed its types, color, or so on.
2018-07-13: Each Storm's triggered ability can copy the Storm spell even if that spell is countered before that ability resolves.
2018-07-13: The copies are created on the stack, so they're not “cast.” Abilities that trigger when a player casts a spell (such as the Storm's ability itself) won't trigger.
2018-07-13: If the copied artifact is a token, the token that's created copies the original characteristics of that token as stated by the effect that created the token.
2018-07-13: Each copy resolves one at a time. Any abilities that trigger on the artifact token entering the battlefield resolve before the next copy resolves. The original spell is the last to resolve.
2018-07-13: If the copied artifact has {X} in its mana cost, X is considered to be 0.
2018-07-13: Each Storm's triggered ability counts only how many times you've cast your commander from the command zone before that triggered ability resolves. If you cast your commander again later, you won't get another copy.
2018-07-13: Any enters-the-battlefield abilities of the copied artifact will trigger when the token enters the battlefield. Any “as [this artifact] enters the battlefield” or “[this artifact] enters the battlefield with” abilities of the chosen artifact will also work.
2018-07-13: If your commander was countered, that time you cast it still counts.
2018-10-05: If you have multiple commanders, you'll copy this spell for each time you've cast either of them. For example, if you've cast one commander once and one twice, you'll copy this spell three times.