Cheapest priced copy (Commander 2015): $0.35 at Card Kingdom, near mint, their price list as of .
Plaxmanta 
Creature — Beast · 2/2 · Uncommon · Dissension · #29
Flash
When this creature enters, creatures you control gain shroud until end of turn. (They can't be the targets of spells or abilities.)
When this creature enters, sacrifice it unless {G} was spent to cast it.
Legal inCommanderModernLegacyVintage
Not legal inBrawlStandardPioneerPauper
3 printings · $0.35 to $2.99 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Commander 2015 | 100 | Uncommon | $0.35 | — |
| Dissension | 29 | Uncommon | $0.39 | $2.99 |
| The List | DIS-29 | Uncommon | $0.35 | — |
One ruling from Wizards of the Coast
- 1 May 2006If this enters in a way other than announcing it as a spell, then the appropriate mana can't have been paid, and you'll have to sacrifice it.