As a spell or ability an opponent controls resolves, if it would force you to sacrifice a permanent, you just don't. That part of the effect does nothing. If that spell or ability gives you the option to sacrifice a permanent (as Desecration Demon does), you can't take that option.
Sigarda's ability affects only sacrifices. It won't stop a creature from dying due to lethal damage or having 0 toughness, and it won't stop a permanent from being put into its owner's graveyard due to the "legend rule." None of these are sacrifices; they're the result of game rules.
If a spell or ability an opponent controls states that something happens unless you sacrifice a permanent (as Mogis, God of Slaughter does), you can't choose to sacrifice a permanent. On the other hand, if a spell or ability an opponent controls instructs you to sacrifice a permanent unless you perform an action (as Killing Wave does), you can choose whether or not to perform the action. If you don't perform the action, nothing happens, since you can't sacrifice any permanents.
Last observed on Scryfall 2 months ago at $6.12. Over the trailing 90 days the price moved between $0.30 and $6.12 across 44 observations. Cross-checked across TCGplayer, eBay sold, Cardmarket EU, and Star City.
This printing is one of 3 catalogued treatments from UMA — the lineup includes Foil and 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 #206 of *Ultimate Masters*, the set that shipped alongside the December 2018 Ultimate Masters release.
Card type: Legendary Creature — Angel, color identity green/white, printed at mythic. Mythic rares historically land in roughly one out of every eight boosters at standard print densities. Mana cost: {2}{G}{W}{W} (5 converted). Keyword abilities: Flying and Hexproof.
Legal across the major constructed formats — Modern, Legacy, Vintage, and Commander — plus Standard rotation play.
EDHrec ranks this card #5,927 in Commander, putting it in the niche-pick tier of the format's playable pool.
Illustrated by Chris Rahn. Rarix catalogs 1,209 other cards credited to this artist.
Magic: The Gathering · ™ & © Wizards of the Coast · Illus. Chris Rahn
Card data via Scryfall. Rarix is fan-made; not endorsed by the rights holders.
