Cheapest priced copy (Jumpstart 2022): $0.79 at Card Kingdom, near mint, their price list as of .
Engulfing Slagwurm 
Creature — Wurm · 7/7 · Rare · Scars of Mirrodin · #118
Whenever this creature blocks or becomes blocked by a creature, destroy that creature. You gain life equal to that creature's toughness.
Legal inCommanderModernLegacyVintage
Not legal inBrawlStandardPioneerPauper
2 printings · $0.79 to $4.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Jumpstart 2022 | 655 | Rare | $0.79 | — |
| Scars of Mirrodin | 118 | Rare | $0.79 | $4.49 |
5 rulings from Wizards of the Coast
- 1 January 2011Engulfing Slagwurm’s ability triggers and resolves during the declare blockers step. Creatures destroyed this way will not deal combat damage.
- 1 January 2011If Engulfing Slagwurm’s ability resolves and the other creature is not destroyed (perhaps because it has already left the battlefield or it regenerates), you’ll still gain life equal to that creature’s toughness.
- 1 January 2011As each ability resolves, the amount of life you gain is equal to the appropriate creature’s current toughness (if it’s somehow still on the battlefield), or its toughness as it last existed on the battlefield (in all other cases).
- 1 January 2011Even if the ability of an attacking Engulfing Slagwurm destroys each creature blocking it, Engulfing Slagwurm won’t deal combat damage to the player or planeswalker it’s attacking unless it somehow gains trample.
- 1 January 2011If your Engulfing Slagwurm blocks or becomes blocked by multiple creatures, its ability triggers that many times. Each trigger will be associated with a specific creature. You choose which order to have the abilities resolve.