Cheapest priced copy (Fifth Edition): $0.35 at Card Kingdom, near mint, their price list as of .
Serra Bestiary 
Enchantment — Aura · Common · Homelands · #15
Enchant creature
At the beginning of your upkeep, sacrifice this Aura unless you pay {W}{W}.
Enchanted creature can't attack or block, and its activated abilities with {T} in their costs can't be activated.
Legal inCommanderLegacyVintagePauper
Not legal inBrawlStandardPioneerModern
2 printings · $0.35 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Fifth Edition | 60 | Uncommon | $0.35 | — |
| Homelands | 15 | Common | $0.35 | — |
2 rulings from Wizards of the Coast
- 4 October 2004Does prevent the use of activated mana abilities with {T} in the cost.
- 8 June 2016Activated abilities contain a colon. They're generally written "[Cost]: [Effect]." Some keywords are activated abilities and will have colons in their reminder text.