Yar, I be the lazyman's BLU in Dynamis.
Usually shit dies too fucking fast-- by the time I engage the mob, I can't do shit. So rather than idly running about, I sub SAM, stack on all my BLU DD spell gear (mostly STR), load up on STR spells + Vertical Cleave, then Meditate -> Spam Vertical Cleave on everything. Usually Cleaves land on everything for about 800~1500 dmg with CA (400~800 without), and mirrors Darkness for the same amount if I happen to chance it after Asuran Fists from random MNK.
When we fight a THF or a PLD that has 2hred, the same gear doubles as a mini-Heat Breath build; HB lands unresisted for 700 dmg a pop usually, knocking off whatever HP the mob has left. Then I set Actinic Burst for the odd MNK and NIN mob.
It's fun shit lol.