
Tortilla |
Very good question, and one that has caused me to put in a lot of research. Fake Healer is correct and thorough in those posts. The only thing I have left to add is that temperatures of -20 f or lower cause lethal damage and do not allow a save. While that does seem to enable the cold buffing strategy, the Golem, Wood entry states: A magical attack that deals cold damage... Therefore, environmental cold damage doesn't seem to be harsh enough to cause buffing.
That being said, yes, a spell caster with cold damaging spells could buff a Golem, Wood, but I'm not sure how long those temporary hit points last, nor what limit there might be. The books seem relatively unexplanitory (at least the Core and Bestiary, as well as 3.5 resources were).
Per Manual of the Planes, 3.0, the Positive Dominant Energy trait of the Positive Energy Plane, there is a limit of double your natural hit points that you can reach before exploding to death outright. It is, however, a specific danger of the plane because high energy areas aggressively fast heal you. If you DM, and players abuse Cold Buffing with their Golems, Wood, you might consider implementing critical mass type temporary hit point rules.