bonus round works like this
1 resolved means when you cast future spells you get 1 copy.
if you cast a 2nd bonus round (or the 1st one a second time via PiF)
cast bonus round (copy on stack). 2 total resolve.
now if you cast a spell, you will get 3 copies.
if you cast a bonus around again it will look like this
cast bonus round (BR trigger, BR trigger, BR trigger). resolve them all, now you will get 4 more copies.
cast something like manamorphose and you get 7 copies
the number of copies is following the pattern: (2^n) - 1 to determine the number of copies. you can just do 2^n to determine total number of spells that will resolve if all copies resolve.
also referred to as Mersenne Numbers,
https://en.wikipedia.org/wiki/Mersenne_prime
bolt damage would be 6, 12, 24, 48, 96 damage etc. i liked bolt in the reforge builds b/c if you cast 1 or 2 bonus rounds and cast a reforge, you can win before reforge and the copies fully resolve if need be (and in a a circumstance where you might get decked (assuming all your bolts aren't in the last X cards)