Cheapest priced copy (Iconic Masters): $0.35 at Card Kingdom, near mint, their price list as of .
Jhessian Thief 
Creature — Human Rogue · 1/3 · Uncommon · Magic Origins · #62
Prowess (Whenever you cast a noncreature spell, this creature gets +1/+1 until end of turn.)
Whenever this creature deals combat damage to a player, draw a card.
Legal inCommanderPioneerModernLegacyVintagePauper
Not legal inBrawlStandard
2 printings · $0.35 to $0.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Iconic Masters | 61 | Common | $0.35 | $0.49 |
| Magic Origins | 62 | Uncommon | $0.35 | $0.49 |
3 rulings from Wizards of the Coast
- 22 June 2015Any spell you cast that doesn’t have the type creature will cause prowess to trigger. If a spell has multiple types, and one of those types is creature (such as an artifact creature), casting it won’t cause prowess to trigger. Playing a land also won’t cause prowess to trigger.
- 22 June 2015Once it triggers, prowess isn’t connected to the spell that caused it to trigger. If that spell is countered, prowess will still resolve.
- 22 June 2015Prowess goes on the stack on top of the spell that caused it to trigger. It will resolve before that spell.