Summoner and some tight DPS check

[Puwarh]

As a summoner I find some trouble when it comes to a very tight DPS check with many target to deal with like the final boss of Tam-tara HM or Garuda plums.

What I do will be
- in loose group like tam-tara HM , focus my pet (garuda for sure) to the same target, bio + ruin II untill one down and switch target. still there are damn multiple adds to kill. I cannot keep doing 3DoT + feaster due to it's cool down and casting time and I can do that for only 3 of them but I have to deal with 10+ of them
- in tight group like garuda's plum, miasma 2 to the group then spam blizzard II, and use all garuda's AOE still it's 4 group to deal with.

I think we are specialize in dealing massive damage in long term not bust them out.

Any suggestion for improvement? Please tell