You have to attack 2 white skull opponents for full veteran XP, not 1 whites.
Announcement: Update to Veteran XP ranking system!
We know that you’ve all been working towards getting those Veteran ranks for your Units and we’ve made a slight change to the ranking system.
Previously, Units earned Veteran XP at the same level regardless of the base difficulty.
Going forward, 0 Skull bases with not reward any Veteran XP and 1 White Skull bases will reward Veteran XP at a 50% rate.
Two White Skull and up ranked bases will reward Veteran XP at the full amount.
This newly implemented Veteran XP ranking system will be the standard for how Veteran XP is now accumulated during normal circumstances.
So if you want to get those Units to Veteran status you’re going to have to put in a little more effort to reach your goal!
Tip: If you are under lvl 30, you can rent Riot unit, also you can use damage perks and damage attack card for more veteran XP per bullet.