Arcane Burden

You impose unnatural weight upon unstable arcane energy surrounding a creature.

One creature within range must succeed on a Constitution saving throw or have its speed reduced by 10 feet until the start of your next turn.

If the target is concentrating on a spell, it has disadvantage on the next Constitution saving throw it makes to maintain concentration before the end of your next turn.

If the target casts a spell before the start of your next turn, its speed becomes 0 until the end of that turn.