When Mask of Immolation enters the battlefield, create a 1/1 red Elemental creature token, then attach Mask of Immolation to it.
Equipped creature has "Sacrifice this creature: It deals 1 damage to any target."
Equip {2} ({2}: Attach to target creature you control. Equip only as a sorcery.)
No player may take any actions between the time you create the Elemental token and the time Mask of Immolation becomes attached to it.
The equipped creature is the source of the activated ability and the source of the damage, not Mask of Immolation. This means that a green creature equipped by Mask of Immolation may deal damage to a creature with protection from red but may not deal damage to a creature with protection from green.