In the begining it's kinda tough to overcome new enemies. Just focus on upgrading your skills first (grenades are sweet), and get ancient rage recharging skill and special life steal skill ASAP. With these you easily beat the game AND later surival mode.
Do not spend a single kred/dollar on this stuff guys! Let's show them that we do not appreciate this kind of crap here and we won't tolerate it anymore.
You gained enough XP from doing Jobs to advance in levels. Now try the Bosses, the PVP, all the other good stuff!