Arcancross Amulet

At the end of a long rest select a school of magic to attune the amulet to. Once attuned you gain the following features:

• You gain a bonus to your spell attack and spell DC equal to half your proficiency bonus rounded down (minimum 1) when casting spells from the attuned school.
• You have advantage on saving throws against spells belonging to the attuned school. If a spell from this school allows you to make a saving throw to take only half damage, you instead take no damage if you succeed on the saving throw, and only half damage if you fail.
• If you see a creature within 60ft casting a spell, you can use your reaction to attempt to change the spell's school to match the attuned school. The DC equals 10 + the spell’s level. On a success the creature's spell is transformed into a spell of your choice from the attuned school. ‪Your choice must be the same level as the triggering spell or be able to be cast at the same level. If your roll exceeds the DC by 5 or more you can choose a new target within 30ft otherwise the spell affects the intended target(s).
  You can use this feature a number of times equal to half your proficiency bonus rounded down (minimum once.) If you fail an attempt to transform a spell, the feature can’t be used again until after your next long rest.

Notes: Transform Spell. You can use this feature a number of times equal to half your proficiency bonus rounded down (minimum once.) If you fail an attempt to transform a spell, the feature can’t be used again until after your next long rest. You gain a bonus to your spell attack and spell DC equal to half your proficiency bonus rounded down (minimum 1) when casting spells from the attuned school., Long Rest