Amulet of Spell Sustaining

 This amulet binds itself to the magic of its user, sustaining a spell that the attuned wearer has cast. As a bonus action, the caster can shift any concentration spell to the amulet to sustain instead of them, allowing them to cast a second concentration spell if they wish. A bonus action on consecutive turn is required to shift concentration of a spell from the amulet back to the caster. A spell sustained by the amulet can no longer be moved or changed, such as Flaming Sphere or Moonbeam. In addition, the DC for an active spell the amulet is sustaining is lowered by your spell casting modifier, now equaling 8 + your proficiency modifier.

You may cancel any spell the amulet is sustaining as a free action. The amulet holds a number of charges equal to 2 x your character level. At the start of your turn, if the amulet was sustaining a spell since the previous turn, subtract the level of that spell from the number of charges in the amulet. If the number of charges in the amulet is lowered to -1 or lower, the amulet shatters and cannot be restored, and any spell it was sustaining is lost. If the caster falls unconscious while the amulet is sustaining a spell, the spell is lost as if the caster had been concentrating on it. If you take damage while the amulet is sustaining a spell, you do not have to make a concentration check for the amulet to maintain the spell, only for a spell the caster may be personally concentrating on.

At each dawn, the amulet regains a number of charges equal to 1d6 + your spell casting modifier. If you have multiple spell casting modifiers you may only add the largest one. The amulet loses all charges every time a user attunes to the item, always starting at 0 charges once attunement is complete.