Unbelievably high amount of resists on necro DOTs

[letsallkillandy]

I've been leveling in Kurns Tower since about level 11 and am now 17 but even now my dots only do HALF damage on dark blue and light blue cons. What gives?

Anything I cast on takes half ticks regardless the spell (darkness / heatblood / heart flutter). The only full damage I can stick on the undead here are undead nukes and life taps. Am I doing something wrong to not make my DOT's hit for full damage? It's pretty depressing to rarely see a full tick on dark blue / light blue cons.

Thanks in advance.