from what i see on 2moons.mmosite.com, the mobs in df have low psihical resistance and some 15% L,I,P ressistance. so if that site is right then some melee in a combo with 1-2 mages can do it ez mode. ofc with skill hack.
as u can see the worse class here is the seg and staff summoner.
Lava Basilisk [Duke] Resistance: F=35%
Lava Salamander [Duke] Resistance: F=35%
Serpent Fate [Duke] Resistance: P=10%, P=35%
Serpent Bartux [Duke] Resistance: P=35%, C=45%
Lava Drake [Duke] Resistance: F=35%
Volcanic Algol [Duke] Resistance: P=10%, F=35%
Kauldras [Duke] Resistance: F=45%
Freyzard [Duke] Resistance: P=10%, F=35%, I=10%, L=10%
Serpent Nodle [Duke] Resistance: P=35%
Serpent Stun [Duke] Resistance: P=35%, C=45%
Las Alhage [Duke] Resistance: P=15%, F=75%, I=15%, L=15%, P=15%, C=45%
Serpent Caput [Duke] Resistance: P=45%, C=25%
Serpent Cuwood [Duke] Resistance: P=35%, C=45%
Magirocci [Duke] Resistance: P=15%, F=45%
Hydras [Duke] Resistance: F=45%, C=45%
Magimata [Duke] Resistance: P=15%, F=45%
Serpent Spawn [Duke] Resistance: F=75%, I=75%, L=75%, P=75%, C=95%
Oppucus [Duke] Resistance: F=15%, F=30%, I=30%, L=30%, P=75%, C=65%
so here are all the mobs with theyr ressitance. so as i`ve said melee+mages can do it :p