AFAIK the only 8th level special ability so far is Pritchard Hood's 'Compel Undead' skill, which is creepy, powerful, and in line with his character.
Last night generated my idea for Roland's. And, now 8th level, my cleric gets one, too. Here are two ideas.
Following the mutual slaughter against the Eyedrinker Tribe, the double-size Roland, Lord Zanzibar &c picks up the Potion of Growth he threw down to expand his size. Enveloped within his massive hand, he sniffs at the thing, then sips the dregs. Faint reason thuds into the fighter's scant brains: This was no potion at all! It was… water!
Roland, Lord Zanzibar, Ant-Man, &c could double his size, as per a potion of growth - once per day - all along! The Sword Princes of Neutrality have conferred this upon him, doubling his neutrality upon the world for a little time. As neutral as they are, they didn't bother to tell him!
I've been bouncing some ideas around. One idea was projecting a permanent Protection from Evil, 10' Radius effect, as per an AD&D Paladin. But then I realized I get an extra 1st/2nd/4th level spell now and that 4th level spell can just be used for that purpose.
Other ideas include permanent Bless effects, something to do with Negative Plane Protection or Restoration (e.g. allowing saving throws for companions), access to one of the 6/7 level Cleric spells in later editions like Flame Strike, Heal, or Blade Barrier. But I'm now thinking:
Summon Valkyries/Sisterhood Spearmaidens.
Seff is associated with the feminine spirits of vengeance and honest battle, who collect the dead and select the slain. This would work like a Horn of Valhalla, where instead of generating Viking-constructs, it generates ghostly forms to aid in combat selected from the sect's ancient orders. Something like 1d4+1 spirits of, say, fifth level, with plate/shield/spear, magical striking properties but no bonuses, who last for a certain number of rounds or until dissipated/slain, who can become intangible and move over water/through allies. Maybe 1 turn/level.