Cheapest priced copy (Rise of the Eldrazi): $0.35 at Card Kingdom, near mint, their price list as of .
Lust for War 
Enchantment — Aura · Uncommon · Rise of the Eldrazi · #157
Enchant creature
Whenever enchanted creature becomes tapped, this Aura deals 3 damage to that creature's controller.
Enchanted creature attacks each combat if able.
Legal inCommanderModernLegacyVintage
Not legal inBrawlStandardPioneerPauper
1 printing · $0.35 to $0.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Rise of the Eldrazi | 157 | Uncommon | $0.35 | $0.49 |
2 rulings from Wizards of the Coast
- 15 June 2010If, during its controller's declare attackers step, the enchanted creature is tapped, is affected by a spell or ability that says it can't attack, or is affected by "summoning sickness," then that creature doesn't attack. If there's a cost associated with having that creature attack, its controller isn't forced to pay that cost, so the creature doesn't have to attack in that case either.
- 15 June 2010Lust for War's triggered ability triggers when the enchanted creature becomes tapped for any reason, not just when it attacks.