They charge from off screen, turns around very quickly and charge again. The window to attack them is small.
I tried shooting with Strike Needle, but they often get out of range so fast, the spread bullets do minimal damage. I tried charging swords (DTB, DA or Combuster), but it's hard to get right behind their backs to unleash it, since they start charging again so soon. And they have good HP in 4-men parties, meaning you need several attacks to kill them only for Vana to summon new ones.
I tried a 2-men party earlier today - a first for me - things were good until the Slag Guards appeared. I was on Shiver duty, but I couldn't keep them all trapped. My partner were supposed to kill the Slags, but he didn't - or couldn't, so he turned to shoot Strike Needle at Vana. Among the charging, shadwo fire and mace, we couldn't deal damaged without taking hits ourselves. We gave up after 1 energy revive from each.
I can handle it in full parties - 4 people means you get to shiver, blitz, and have two people left to water and keep the Slag Guards busy, even when you can't kill them fast enough.
But it seems very hard in a 2-men party. What's your strategy?
- Two shiver to keep everything immobile, heal up with hearts that eventually appear and blitz when you have free time?
- Is there some secret to dodging Slag Guards?
- Is there some secret to killing them fast?
As a slag baiter, I usually stick to the left or right wall, guessing the time when they'll charge, and moving in a semi circle around to dodge and hit their back with a DA. Works best if there's another player to the other side doing the same, or if you have a FoV to launch charge attacks with. Sometimes I keep a slag at the bottom or top, but the bottom area is where teammates head towards to get a better view, so yeah. Shivering slags requires a lot of moving around and estimating charges, from what I've seen. Killing them fast? For me, I use FoV/well-timed DA charges. Dodging them? I estimating the time of their attacks from experience. Dodging early instead of blocking helps a lot, too, if you have lag.
Edit: For a two-man party, you could try moving to the lower part of the screen to see their charges and dropping shivers to freeze them in place. Bonus if you can get Vana to charge into the mist. You might also want to keep one frozen and go after the other, and return to take out the remining one, while keeping Vana frozen, and returning your efforts to taking out Vana after.