Arcane Channeller

Having spent a significant portion your life learning the intricacies of magic, you have mastered the rare art of co-casting spells in conjunction with other magic users.

When you hold your action or bonus action to cast a spell, as turns pass, other casters with this feat may join in its channelling. To do so, they expend a spell slot of the spells initial level, then end their turn holding their action to join in the casting of the spell, and choose one of the following effects:

• Divide the original casting time requirement by the number of channellers joined in the casting.
• Increase the level of the spell by one.
• If the spell would make a ranged attack roll or require a single target to make a saving throw, create a copy of the spell in it's current channelled state, and pick a target for the copy.
• Grant advantage to the channelled spell's ranged attack roll when it is cast. Or,
• Bestow disadvantage on any saving throws the casting of the modified spell causes.

All channellers joining a casting are concentrating on the modified spell until it is cast, regardless of whether the original spell is a concentration spell. If a single channelling caster loses concentration on the channelled spell before it is cast, the modified spell fails, and all expended spell slots are lost.