^
I tend to setup (depending on the tier) near the Biv. Toss down Geo-Refresh, keep Indi-Acumen up full time. Tier III or lower and I tell the group I've got the Biv covered, though pugs are usually hesitant to believe me, til they're unable to get a swing off on a mob lol. Acumen + gear (varries of course) allows for Stone II to one shot all magic weak mobs except for Luckybugs. Stone IV will one shot most non-magic weak mobs. Stonera I will one shot a group of magic weak mobs, and Stonera II > Stonera I will take out groups of anything.
Think the only thing I really have much of an issue with killing is Panomts (stone seems to resist more than other elements, pretty much just started using Fire IV to one shot and not have to deal with them) and Belladonnas. Belladonnas more so because of the knockback and interruptions, but if you're paying attention and see them coming, Thunder IV one shots (I think, haven't ran a tier V in a week at this point.)
As the previous poster mentioned too, Radial Arcana (not that its not normall useful) and Mending Helation are actually really useful abilities for an event like this. Keep Blink/Stoneskin/Phalanx/Aquaveil* up for when larger waves come and you don't have time to cast higher tier spells to one shot everything and you'll be fine.
*Aquaveil is stupidly important for this. I don't know if Blm has less of an issue with this, but Geo's get absolutely wrecked with spell interruptions once Blink/Stoneskin/Aquaveil are down and a few mobs are on them, just absolutely no chance to get a spell off unless you time it inbetween hits.