Shared Pain & Magic Staff - If the staff does not do any damage (but does not miss), yet gets to use its surge ability to damage a nearby monster, does Shared Pain's effect happen; if so, to which monster group? This question applies to Blast victims as well…
Here's the text on Shared Pain, for reference:
"Action: Perform an attack. If you deal at least 1 [Heart] (after rolling defense dice), each other figure in the target's monster group suffer's 1 [Heart]."
The operative word in this sentence is "target." The target monster is the monster which occupies the target space of the attack. Any attack has only one target space, additional affected figures due to AoE are not "targets." Likewise, the secondary damage inflicted by magic staff does not make that monster a "target" either.
Therefore, the answer is that you must deal at least one [Heart] to the original target monster for this effect to kick in. Only other monsters from the target's monster group will be affected.
Ancestor Spirits - Does this ability affect each figure affected by the triggering ability (Shared Pain for monsters, Vigor or Drain Spirit for heroes), or just 1? Also, for heroes, the card states that affected heroes gain 1 each health/fatigue; which of the following is correct for a hero that has been healed 3 health by Healing Rain? 1) The hero is healed 3 health and 3 fatigue. 2) The hero is healed 5 health and 1 fatigue.
Ancestor Spirits does not use the word "target" therefore it can be applieed to any monster or hero who was affected by the other ability. However, Ancestor spirits only works on "a monster" or "a hero." Even if multiple figures are affected by the other ability, you can only choose one to be affected by Ancestor Spirits.
A hero healed for 3 health by Healing Rain would gain a total of 4 health and 1 fatigue with Ancestor Spirits thrown in.