AnonymUser
I like 1 the best as it is the most versatile increase without any drawbacks. 4 was also on my mind but was discarded because of the inherent vulnerabilities that it would introduce. While it was mentioned that the MC can use his fire, affinities, and domains to pissibly make up for it, that still leaves an opening to enemies with domains or abilities that can mimic (cold domain) abilities, cancel, or stun him. In conclusion, I think 1 is best for him at this time since it is strong, versatile, and leaves options open for abilities similar to the others to be obtained in the future.
4. you cant go below -273.05°C so at worst the ability would be -2 STR debuff. But MC has over tausend of STR, so the ability in worst case will be BASE=BASE-2 STR 1000->998 or some such of a negligeable debuff. if it is not a buff but it makes the STR stat a set value aka... BASE=-2 STR 1000->-2 then its not worth even thinking about.