And how many 10 star heroes do you have? ULFPAM is right, if your only 10* hero is Dog (as I am sure it is for most F2P/newer players), then you will want the extra hero frags. If you have 5 or 6 10* heroes then you can get plenty of frags from PVP and it’s not nearly as valuable investing in them with Gauntlet gems.
The OP was talking about not having any 10* heroes, soo…
