Gift of Reason and items slots

[atul]

Depends on unit.

Tarrasque, for example, has only two misc slots, nothing else. Humanoids usually have at least most of the slots.

[Wick]

You can just download one of the all units maps and look at all of them.

[Boron]

In short only Mind Enslaved enemy SCs + Tartarians + Wished Creatures ( Doom horror , Ettin Mandragora , AQ , Nataraja etc. ) are worth being GoRed .
A Gargoyle might be worth a GoR too .