H3LI0S
Will the MC find a way to use the heat blast's ice powers? because he has this power when he catches a cold, and it's a pretty cool ability to have even though there are other aliens with ice powers in this universe none of them appear until ben is at least 11 years old or 1 year after summer vacation
As for the power that has a high (almost non-existent growth limit), I would give it Genetic manipulation. DNA vision (the ability to see the DNA of other beings and compare it with your DNA and others), even if it was purely theoretically possible to hybridize different species, the main character could create it, if he was evil he could kidnap people similar to himself in terms of DNA, and modify. Imagine that he accidentally finds a species that can control time and space. It could create a breach in this universe and goes on to others.