Ariadne was in such a hurry to get ALLLLL her flying seahorses that she forgot all about filling her jar with water. She had almost starting casting the charm, when she remembered that she didn't do this. OOPS. Sorry, ickle flying seahorses! Was she supposed to just run to the lake and fill the jar up with water? Where was this water supposed to come from?!

...oh, right. She was a WITCH. She had this little thing called a WAND.

Duh, Ariadne.

She flicked her wand out her holster and aimed it into the jar. "Aguamenti!" she said, waving her wand in a sideways S shape. She watched the water as it began to fill the jar. When it was almost to the rim, she flicked her wand and said, "Finite!" The water stopped coming out her wand, and she was left with a filled jar just READY for loads of flying seahorses.