Cheapest priced copy (Dragons of Tarkir): $14.99 at Card Kingdom, near mint, their price list as of .
Sidisi, Undead Vizier 
Legendary Creature — Zombie Snake · 4/6 · Rare · Dragons of Tarkir · #120
Deathtouch
Exploit (When this creature enters, you may sacrifice a creature.)
When Sidisi exploits a creature, you may search your library for a card, put it into your hand, then shuffle.
Legal inCommanderPioneerModernLegacyVintage
Not legal inBrawlStandardPauper
4 printings · $14.99 to $34.99 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Dragons of Tarkir | 120 | Rare | $14.99 | $24.99 |
| Dragons of Tarkir Promos | 120p | Rare | $22.99 | $34.99 |
| Dragons of Tarkir Promos | 120s | Rare | — | $18.99 |
| The List | DTK-120 | Rare | $14.99 | — |
5 rulings from Wizards of the Coast
- 25 February 2015You can sacrifice the creature with exploit if it's still on the battlefield. This will cause its other ability to trigger.
- 25 February 2015You choose whether to sacrifice a creature and which creature to sacrifice as the exploit ability resolves.
- 25 February 2015A creature with exploit "exploits a creature" when the controller of the exploit ability sacrifices a creature as that ability resolves.
- 25 February 2015If the creature with exploit isn't on the battlefield as the exploit ability resolves, you won't get any bonus from the creature with exploit, even if you sacrifice a creature. Because the creature with exploit isn't on the battlefield, its other triggered ability won't trigger.
- 25 February 2015You can't sacrifice more than one creature to any one exploit ability.