Slither cancels Hunter's Mark. Giving your position as a healer is bad, so it may be a good idea to slither away to get rid of it. You can still heal your teammates from a distance!
Avoid stacking up in a line as you attack or your team will get speared with a presence shot for 800 piercing damage. Be wary if you see a Lian with Eminence as it will focus on presence spam. Stay behind shields as it cancels on hit effects.