Cheapest priced copy (Double Masters 2022): $0.79 at Card Kingdom, near mint, their price list as of .
Thraximundar 
Legendary Creature — Zombie Assassin · 6/6 · Mythic · Alara Reborn · #113
Haste
Whenever Thraximundar attacks, defending player sacrifices a creature of their choice.
Whenever a player sacrifices a creature, you may put a +1/+1 counter on Thraximundar.
Legal inCommanderModernLegacyVintage
Not legal inBrawlStandardPioneerPauper
6 printings · $0.79 to $17.99 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Double Masters 2022 | 287 | Rare | $0.79 | $0.99 |
| Double Masters 2022 | 546 | Rare | — | — |
| Alara Reborn | 113 | Mythic | $0.99 | $17.99 |
| Commander 2013 | 221 | Mythic | $0.99 | — |
| Commander 2013 Oversized | 221 | Mythic | — | $0.99 |
| Secret Lair Drop | 142 | Mythic | $8.99 | — |
2 rulings from Wizards of the Coast
- 1 May 2009Thraximundar's middle ability resolves during the declare attackers step. The defending player sacrifices a creature before it would get a chance to block.
- 1 May 2009Thraximundar's last ability triggers whenever any player (including you) sacrifices a creature for any reason. It doesn't trigger only when a creature is sacrificed due to its middle ability. Note that Thraximundar itself doesn't allow you to sacrifice any creatures.