Samael
Spawns a sigil underneath Isaac, up to a maximum of 5, with each sigil being linked to the previous one.
Upon trying to spawn a 6th sigil or by double-clicking, Isaac slashes through each sigil, damaging enemies caught between them and ones nearby.
Amount of damage dealt is determined by a formula: 1 × TearsStat × DamageStat × (0.666 * Sigils crossed) with the latter being a combo bonus. The damage dealt by Memento Mori cannot be lower than 0.6.
The amount of times damage is dealt is determined by how many tears Isaac fires at once (items such as Loki's Horns, Mom's Eye, or Eye Sore are unaccounted for).
Every slash inherits Isaac's tear effects.
Slashing also gives a brief window of invulnerability and a very slight push afterward, which also allows dashing through spikes, and entering Curse Rooms for free.
Sigils and sigil links change their color and overall appearance depending on Isaac's tear color and certain items.
Unlock: Defeat Delirium as Tainted Samael.