The only 4* in the Ice Breaker token pool is Iceman, with base odds of 3.6% per draw, up to 4.8% for a 10/40-pack. But those are last season’s 4* odds - as of Season XIX, the chance of a 4* pull from tokens is 4.6% (specific figure, including significant figures, confirmed here). Bobby Drake says: Not cool!
(Edited to add: 2* odds in Ice Breaker are 5.6% per character. In heroics, 5.5%. So, yep.)