What does it take to make BST useful in w3 dyna? I have heard some groups use them for the slug debuff. I would like to try it but don't want to invest a lot of time into getting +3 AF and relic gear, would prefer to use some carryover gear from other jobs if possible.
Not much, just to make it useful. If you aren't going to be meleeing then just master, -Ready timer gear, and maybe some basic pet macc gear since Purulent Oooze can be resisted. If you are meleeing then do the TP sets from the front page with Ambu axe, the Decimation set, a DT set, and that's a wrap. BST isn't a heavy DD but the Doli/Decimation combo combines the utility with enough dps to justify the slot IMO.
Agreed with Beanen, I do slug for wave 3 boss, Unleash > Purulent Ooze until that effect lands, Corrosive Ooze, then either Sweeping Zhivago or my favorite, Fluffy Bredo, who is great for magical setups since he gets MDB-25 plus he does moderate dark damage.