Many thanks, Laddinfance, for taking time to resolve this. Much appreciated. Great news about the impending FAQ.
You were right, Zuberi and sIKE. Time to re-evaluate the tricksiness of the Forcemaster. And the value of Psychic Immunity.
I have a related question that someone may be able to answer....
"Spell Traits That Affect Your Spellbook" (p36) state "Mage Class Only" or "School of Magic Only" traits only affect inclusion in a spell book, not control.
Hence a Wizard may Steal a Warlock's Death Link and move it to his Bloodreaper.
A Forcemaster may Steal a Warlord's Helm of Command if he has no head slot item.
A Forcemaster may Mind Control a Beastmaster's Felella or a Wizard's Huginn.
What about a spell bound to the newly controlled target? I assume it is hijacked by the controller, just like the buffs on a Mind Controlled Grizzly. But just like those buffs, you don't control the spell bound. If changed, it returns to its owner's spell book as the controller of that spell is the owner. This approach would mean that if you take control of Felella who has Nullify prepared, that Nullify if cast would still be controlled by the opponent. The same would apply to taking control of a Goblin Builder with Akiro's Hammer prepared. But taking control of a Thoughtspore or Huginn with Teleport prepared would allow you to cast that Teleport with you choosing target and destination because Teleport isn't an object.
Was the above approach the right one to take? (The Huginn example actually did happen in a game today.)