Cheapest priced copy (Core Set 2019): $2.29 at Card Kingdom, near mint, their price list as of .
Vaevictis Asmadi, the Dire 
Legendary Creature — Elder Dragon · 6/6 · Mythic · Core Set 2019 · #225
Flying
Whenever Vaevictis Asmadi attacks, for each player, choose target permanent that player controls. Those players sacrifice those permanents. Each player who sacrificed a permanent this way reveals the top card of their library, then puts it onto the battlefield if it's a permanent card.
Legal inCommanderPioneerModernLegacyVintage
Not legal inBrawlStandardPauper
4 printings · $2.29 to $21.99 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Core Set 2019 | 225 | Mythic | $2.29 | $9.99 |
| The List | M19-225 | Mythic | $2.29 | — |
| Core Set 2019 Promos | 225s | Mythic | — | $21.99 |
| Secret Lair Drop (Nergigante, Herald of Destruction) | 2239 | Mythic | — | — |
4 rulings from Wizards of the Coast
- 13 July 2018If any player controls no permanents, Vaevictis's ability won't have sufficient legal targets, so it's removed from the stack without any effect.
- 13 July 2018If any of the target permanents aren't sacrificed (most likely because one of them became an illegal target, such as by gaining hexproof), that permanent's controller won't reveal the top card of their library or put it onto the battlefield.
- 13 July 2018Vaevictis's triggered ability resolves during the declare attackers step, before blockers are chosen. A creature targeted by its ability won't be around to block, and creatures put onto the battlefield with its ability may be able to do so.
- 13 July 2018You must target one of your permanents to sacrifice as well.