Root harnesk would be good of you're struggling with ticks and normal seekers. Atgeir would serve useful in situations where you're being swarmed by ticks and seekers, pretty sure a blackmetal atgeir alt attack one shots normal and one starred ticks, and potentially 2 star ones, as they're weak to pierce. Seeker soldiers are best to parry with a shield and attack their abdomen as it's their weakpoint, just make sure they're alone before you fight them.

I'd say focus on killing ticks first, since if they catch onto you when swarmed and out of stamina, you're going to die in 9/10 scenarios. Kite the other enemies whilst focusing on ticks. You can also use stairs if there's any to filter ticks and normal seekers are soldiers are too big to fit through.

Make sure you clear the room, and any connected ones for enemies that might wander in to ambush you before you open any doors or destroy overgrown roots. It will help you from getting swarmed.

Also when there is a tick on you and you're panicking, remember; if it's on your front, hit it, and if it's on your back, roll to get it off. Dodging when there's a tick on your front might accidentally block their attack, and if you're too low on stamina or health, might stagger you and kill you, happened to me quite a number of times.