Now that we've had the ruling that arcane assassin only works on direct buffs to ARM or DEF:
I thought it might be nice to have a complete list for reference of all the buffs that models with arcane assassin can ignore. I'll start with Warmachine and update with Hordes later if people think this is useful.
First up, the current arcane assassins in Retribution are:
-Garryth, Blade of Retribution
-Mage Hunter Strike Force
-Mage Hunter Strike Force Commander
-Mage Hunter Assassin
-Narn, Mage Hunter of Ios
(It is worth noting that thanks to 'Blessed', Fane Knight Skeryth Issyen ignores all the buffs apart from focus points over boosting a Warcaster's powerfield).
So for Warmachine, the following effects are ignored:
Forward Kommander Sorscha:
The Butcher of Khardov:
Vladimir Tzepesci, The Dark Prince:
-Blood of Kings
Karchev the Terrible:
Zevanna Agha, The Old Witch of Khador: