Little personal experience, but I think OR is for phase 2. McMole once had a video about it. Zaalbar's armor shred, and the assists from Mission (and Young Han if you have him zeta'ed) will do some nice dmg.
I'm guessing geos can only be used in phase 2 as well. They'd kill themselves off quickly against Traya in phases 3 and 4, and the many basic attacks won't work against Nihilus.
I hear people do tons of dmg with DR in phase 3. But will probably require Malak to work properly.
Anyway, interested to see what others will suggest.
