Cheapest priced copy (Kaldheim): $0.35 at Card Kingdom, near mint, their price list as of .
Draugr's Helm 
Artifact — Equipment · Uncommon · Kaldheim · #88
When this Equipment enters, you may pay {2}{B}. If you do, create a 2/2 black Zombie Berserker creature token, then attach this Equipment to it.
Equipped creature gets +2/+2 and has menace. (It can't be blocked except by two or more creatures.)
Equip {4}
Legal inCommanderPioneerModernLegacyVintage
Not legal inBrawlStandardPauper
1 printing · $0.35 to $0.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Kaldheim | 88 | Uncommon | $0.35 | $0.49 |
2 rulings from Wizards of the Coast
- 5 February 2021The Zombie Berserker creature token enters the battlefield as a 2/2 creature. Any abilities that trigger when a creature with a certain power or toughness enters the battlefield will see the token enter as a 2/2 creature.
- 5 February 2021You decide whether to pay {2}{B} as the enters-the-battlefield ability resolves. If you do, you immediately create the Zombie Berserker creature token and attach Draugr's Helm to it. No players may respond to your decision to pay or not, and no player may take actions during this process.