Sins and Blessings is the final stage in Ritual Confusion.
Battleground
Lucky Sloth spawns immediately as a boss.
Dark Otter joins shortly afterward, and will respawn every 36.7 seconds until 4 of them have been seen.
For every 16.7 seconds that pass, a relatively weak Doge Dark will spawn. For the first three times that this occurs, a Lucky Dags will also spawn.
For every 30 seconds that pass, a Metal Hippoe will spawn, until 3 Metal Hippoes have been seen.
After 75 seconds have passed, 4 additional Lucky Dagses will join the fray, with a quicker 6.7-second delay.
Strategy
Break through the Metal Hippoes and Dark Otters quickly by using anti-Black Cats with Massive Damage or Insane Damage abilities and cats that can perform Critical attacks reliably.
Even though the Lucky Dagses are single-target, they can snipe your attackers effectively whenever Lucky Sloth's knockback deactivates the hitboxes of your surviving Erasers. So once no more Metal Hippoes or Dark Otters are around, it is time to pile up your attackers.