This thread is pretty cut and dry; does something stack and how. RAI or RAW.
1) Undeath: Heal—This works like a standard channel (not halved). Harm—The healing effect is enhanced for undead creatures and those with negative energy affinity.
2) Some variant channeling abilities are enhanced when used on particular creature types. Such channeling increases the normal healing or damage from channeled energy by 50% for that creature type, rather than the default half healing or damage for the alternative channeling
3) Unlife Healer (Su)
At 8th level, the undead lord’s spells, spell-like abilities, and supernatural abilities used to heal undead heal an extra 50% damage. At 16th level, these effects automatically heal the maximum possible damage for the effect + the extra 50%. This does not stack with abilities or feats such as Empower Spell or Maximize Spell.
Obviously it's about channeling negative energy. Since it's a variant and not an ability or feat: does the added negative energy from the variant channeling stack with the added negative energy from the class feature?
Do we call it an ability and limit the optimization to 150%? (it doesn't stack)
If it does stack, does it multiply or add to itself? 100% + 50% + 50% = 200% or 150% x 150% = 225%
And lastly; does it all maximize at 16th level?
Discuss.