Blade Ring is one of many spells. It requires level 10 to unlock, and costs 20 mana to cast. At higher levels, it increases damage, duration, and size. It looks like a spinning circle of daggers around the character. As the size increases, a gap appears between Dash and the ring, making it possible for creatures to be inside and not be damaged.
Despite being a spell, Blade Ring does physical damage. It's damage is still affected by intellect, not weapon damage.
At level 6, Blade Ring's base damage is 90. For every point of intellect, it deals 1.80 more damage.
With enough cooldown it can be cast twice before the first spell ends, and both versions will spin around and do damage.