It would be 'under effect constantly'.
It would also be a high-level campaign.
Going over what was suggested:
Truestrike - already has an attacks at +39... would +59 be redundant? And it would only be 1 attack out of the three he gets.
Feint is not useful, no sneak attack or anything.
Anti-magic is bad. He already has a permanent glove of invulnerability
Healing is harder because it must be an arcane spell. Then again, he's a construct. But I think it has to be a buff
True sight - have it permanent
Polymorph - you know, not really useful to this guy
Haste - have it permanent
False Life - Seems weak, actually
Wraithstrike - again, +38 to hit, needing it to be a touch attack is a bit low on the ladder
Now, Repulsion or Displacement... those might be fun...