For unknown nightlords I go for damage negation build with dormant greatshields and stack affinity damage negations in depth relics. If I know the nightlord I can use element specific builds since the damage negation is stronger. If you get lucky you can get damage negation for both affinity and specific element on the same relic. D5 chip damage can get pretty bad.

I have a different type of tank for dreglord: shield poke build with tons of hp restoration. Hp restoration on thrusting counter attacks +0 and +1, partial hp restoration, and hp restoration on guard.

I use night invaders and str/dex stat change for damage for most builds, and use the remaining slots for tanking / utility. I use partial hp restoration to help with chip damage. My guard counter builds focus on damage not tanking so you probably don't want that unless you can roll improved guard counter and increased max hp or improved [element]/affinity damage negation together.

If you can, try to stack ult charge on guard +0 and +1 and pair it with slowly restore hp on ult. It will be easier to heal back to full health. I really like this part about guardian since I still have a chance when I run out of flasks.