I’m at my highest with little over 4600 trophies, so I can’t have experiences with lvl 30 Dracorex gen 2.
Even in my range sometimes crit is needed to oneshot it. Still users od Dracorex gen 2 gamble, hoping that opponent doesn’t have in lineup dino that deals high damage and has high crit chances. Which result in free kill.
A lot depends on RNG choise of lineup for battle. If you have very fast dinos or tanks and at least one remaining dino at ful hp, then Dracorex gen 2 tactic most likely won’t be effective against you, even if you don’t kill it.