Cheapest priced copy (Battlebond): $0.35 at Card Kingdom, near mint, their price list as of .
Jubilant Mascot 
Creature — Homunculus · 1/1 · Uncommon · Foundations Jumpstart · #213
At the beginning of combat on your turn, you may pay {3}{W}. If you do, support 2. (Put a +1/+1 counter on each of up to two other target creatures.)
Legal inCommanderLegacyVintage
Not legal inBrawlStandardPioneerModernPauper
3 printings · $0.35 to $0.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Battlebond | 28 | Uncommon | $0.35 | $0.49 |
| Foundations Jumpstart | 213 | Uncommon | $0.35 | — |
| The List | BBD-28 | Uncommon | $0.35 | — |
5 rulings from Wizards of the Coast
- 8 June 2018Support can target a creature another player controls.
- 8 June 2018If a spell with support has other abilities that target creatures, those abilities and the support ability can target the same creature.
- 8 June 2018You can't put more than one +1/+1 counter on any one target using the support action.
- 8 June 2018If some, but not all, targets for a spell become illegal, the remaining targets are affected as appropriate. If all of a spell's targets become illegal, that spell doesn't resolve.
- 8 June 2018You choose the target creatures to support when Jubilant Mascot's triggered ability is put onto the stack, but you don't choose whether to pay {3}{W} until the ability resolves.