A friend and myself just finished vanquishing Elona and started out a bit perturbed with the groups of Eles in various areas. As mentioned by several folks here, we found a minion master and Pain Inverter works wonders. Normally even FUN to watch

. A little coordination helps also (each of you take a separate target or double up on problematic bosses). We even found this method helpful in Crystal Overlook where you may have to deal with 3-4 Sandstorm Crags or Ruby Djinns in the same group.
Also, as mentioned before, my Ranger is my title hunter and I always had a couple interrupts along with RTW, Experts Dexterity and some "lay the stank" shots in case I have to deal with ones we didn't have enough pain inverters for.
Good luck and if you need a human hand you are welcome to ping us (Lone Scout I ign).