Cheapest priced copy (New Phyrexia): $0.39 at Card Kingdom, near mint, their price list as of .
Act of Aggression 
Instant · Uncommon · New Phyrexia · #78
({R/P} can be paid with either {R} or 2 life.)
Gain control of target creature an opponent controls until end of turn. Untap that creature. It gains haste until end of turn.
Legal inCommanderModernLegacyVintage
Not legal inBrawlStandardPioneerPauper
2 printings · $0.39 to $9.99 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Commander 2015 | 141 | Uncommon | $0.49 | — |
| New Phyrexia | 78 | Uncommon | $0.39 | $9.99 |
7 rulings from Wizards of the Coast
- 1 June 2011As you cast a spell or activate an activated ability with one or more Phyrexian mana symbols in its cost, you choose how to pay for each Phyrexian mana symbol at the same time you would choose modes or choose a value for X.
- 1 June 2011A card with Phyrexian mana symbols in its mana cost is each color that appears in that mana cost, regardless of how that cost may have been paid.
- 1 June 2011If you're at 1 life or less, you can't pay 2 life.
- 1 June 2011To calculate the mana value of a card with Phyrexian mana symbols in its cost, count each Phyrexian mana symbol as 1.
- 1 June 2011Phyrexian mana is not a new color. Players can't produce Phyrexian mana.
- 1 June 2011Act of Aggression can target any creature an opponent controls, even one that's untapped.
- 1 June 2011Gaining control of a creature doesn't cause you to gain control of any Auras or Equipment attached to it.