2x chance actually gives you double the chance to pull an epic or legendary from an ancient/void shard, or a legendary from a sacred shard, during their respective events. 

10x chance DOES NOT increase those odds, at all. It only increases the chance that IF you would  pull an epic/legendary from an ancient/void/sacred, there is a 10x higher chance that you'd pull one of the selected champions, than that you'd pull anybody else. Although considering the number of champions involved, that still leaves you with a relatively low chance of pulling the champions in question. 

Hence, for newer players, it's recommended to ignore 10x events and pull your shards during 2x - because you don't have many top champions yet, so you'd rather have a higher chance of getting any epic/legendary. A possible exception is 10x events in which a very good non-void epic is offered - then you might consider to try pulling some sacreds and hope that you'll get the selected epic (with still a small chance of getting a lego instead). 

10x is more for spenders and endgame players that recieve more shards. 

If you struggle with champ pulls, then 2x is better.  

If u are struggling with the amount of shards and just wanna pull a legendary i would go 2x any time. 10x are mainly if u hunt a specific legendary (or epic) and have a bunch of shards to get started the hunting. 

Great  that  really  makes  sense  thank  you  all  for  your  help!