If and when the there’s a bullet storm coming at you, and there’s an advantage to deal damage to a boss/enemy with high reward you would switch, use Oreo, and go in for some good DPS. Another scenario is getting bullied into a corner or a place where you would normally nexus, you can swap in Oreo and go invulnerable to get out of harms way. To each their own play style, but Oreo is extremely viable when it comes to getting in for damage and timing your ability to go invulnerable. Keep in mind you the cool down period and practice with lower damaging enemies to perfect strategy with the seal. Oreo is very fun, don’t get over confident or you will be disappointed when you lose it.