Cheapest priced copy (Commander Masters): $1.29 at Card Kingdom, near mint, their price list as of .
Pathrazer of Ulamog 
Creature — Eldrazi · 9/9 · Uncommon · Rise of the Eldrazi · #9
Annihilator 3 (Whenever this creature attacks, defending player sacrifices three permanents of their choice.)
This creature can't be blocked except by three or more creatures.
Legal inCommanderModernLegacyVintage
Not legal inBrawlStandardPioneerPauper
4 printings · $1.29 to $6.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Commander Masters | 4 | Uncommon | $1.29 | $3.49 |
| DCI Promos | 46 | Rare | — | $6.49Out of stock |
| The List | ROE-9 | Uncommon | $1.29 | — |
| Rise of the Eldrazi | 9 | Uncommon | $1.99 | $4.49Out of stock |
2 rulings from Wizards of the Coast
- 15 June 2010If a creature with annihilator is attacking a planeswalker, and the defending player chooses to sacrifice that planeswalker, the attacking creature continues to attack. It may be blocked. If it isn't blocked, it simply won't deal combat damage to anything.
- 15 June 2010Annihilator abilities trigger and resolve during the declare attackers step. The defending player chooses and sacrifices the required number of permanents before they declare blockers. Any creatures sacrificed this way won't be able to block.