
Bobson |

I just want a sanity check on this before I use it:
Assuming a troll had cleric levels and could cast shield other, the troll cleric could cast it on all his companions, then hide himself nearby, and he'd effectively be doubling the health of all his companions.
Every time they took damage, he'd take half. Because it loses its type, it doesn't disable his regeneration, even if it's fire or acid damage. Because his regeneration is still up, he can't die from hit point loss. So he could take around 60 damage per companion, go down to -300 or so, and 6 minutes later (5 hp/rnd = 50 hp/minute) he'd be awake again. Provided the party didn't find him and touch him with a match, anyway.

Tarantula |

Considering it is a level 2 spell, just how many companions are you planning on casting it on? Also they all have to remain within the distance of the spell of each other, otherwise it ends. Barring that, yes, the troll would effectively double the HP of his buddies he casts it on.
Not to mention standard trolls have a 6 int, 9 wis, and 6 cha. I think that pretty effectively prevents them from casting.

Bobson |

wouldnt the spell end when the troll hits -1
No, you can die to shield other. I had a player die that way - he had three shield other spells up at once, and then the party got hit by several of the breath weapons from a pyrohydra. So he took damage, and he took half of two or three other player's damage. Even if everyone involved had made their saves, he'd still have exploded.
You don't need a troll...just use an inquisitor. They can cast Shield Other and declare a Judgment of Healing.
Fast healing shuts off when the creature takes enough damage to die. Regeneration prevents the death, so it keeps going. In order to make this tactic work, you have to be unable to die from the hit point damage, which means regeneration.

Lune |

Why carry a whole troll around? All you need is the troll's finger that is wearing the ring. Just make sure that all the other peices of the troll are smaller than the finger so the finger is what the troll regenerates from. Then stick the stub of that finger cork style into a vial of acid so that it can't regrow from the stump.
...then put that finger stump (in the vial) in your pocket.
I like this idea. *yoink!*