The mana value of a permanent is determined solely by the mana symbols printed in its upper right corner, unless it's copying something else (see below). The mana value is the total amount of mana in that cost, regardless of color. For example, a card with mana cost {3}{U}{U} has mana value 5.
If a nonland permanent has no mana symbols in its upper right corner (because it's a token that's not copying something else, for example), its mana value is 0.
Steel Hellkite's last ability destroys only nonland permanents whose mana value is exactly equal to X, and only those controlled by players who have been dealt combat damage by Steel Hellkite this turn.
Last observed on Scryfall 2 months ago at $0.30. Over the trailing 90 days the price moved between $0.30 and $0.31 across 49 observations. Cross-checked across TCGplayer, eBay sold, Cardmarket EU, and Star City.
This printing is one of 2 catalogued treatments from C17 — the lineup includes Nonfoil alongside the standard finish. Across our catalog the Rarix library tracks every variant in the same family so collectors can compare price, scarcity and demand inside a single lineage.
Card #225 of *Commander 2017*, the set that shipped alongside the August 2017 Commander 2017 release.
Card type: Artifact Creature — Dragon, printed at rare. Rares occupy the bottom-of-pack rare slot in standard boosters. Mana cost: {6} (6 converted). Keyword abilities: Flying.
Legal across the major constructed formats — Modern, Legacy, Vintage, and Commander — plus Standard rotation play.
EDHrec ranks this card #1,092 in Commander, putting it in the common-include tier of the format's playable pool.
Illustrated by James Paick. Rarix catalogs 505 other cards credited to this artist.
Magic: The Gathering · ™ & © Wizards of the Coast · Illus. James Paick
Card data via Scryfall. Rarix is fan-made; not endorsed by the rights holders.
If the mana cost of a permanent includes {X}, X is 0 for the purpose of determining its mana value.
In all cases, ignore any alternative costs or additional costs (such as kicker) paid when the permanent was cast.
If a permanent is copying something else, its mana value is the mana value of whatever it's copying.
It doesn't matter who controlled those permanents at the time Steel Hellkite dealt combat damage, or if those permanents were even on the battlefield at that time.
You may activate the last ability even if Steel Hellkite hasn't dealt combat damage to any players that turn. If you do, the ability won't do anything.
If Steel Hellkite's third ability is activated with X equal to 0, it will destroy each nonland permanent with mana value 0 the appropriate players control.
