Arcane Siphon

You attempt to interrupt a creature in the process of casting a spell. If the creature is casting a spell of 3rd level or lower, its spell fails and has no effect and you can cast it on your turn. If it is casting a spell of 4th level or higher, make an ability check using your spellcasting ability. The DC equals 10 + the spell's level. On a success, the creature's spell fails and you can cast it on your turn without spending any material components or spellslots, if you maintain concentration till your turn.