Does dealing damage guarantee bosstiary credit for bosses?

Question

I’ve noticed that on a few occasions, after dying while fighting a boss, I managed to deal some damage but wasn’t present when the boss was finally killed.
Even though I received loot from the reward chest, the boss did not get credit in my bosstiary.

How does this system work? Is there a minimum amount of damage I need to deal to the boss to get bosstiary credit, or does dying prevent it entirely? 

Answer 1

For bosses that have a cooperative loot system, a minimum participation level is required in the fight to guarantee +1 kill on the bosstiary.

The amount of damage you deal is taken into account. In addition, taking damage from the boss and supporting other players during the fight (healing, for example) also helps ensure that you reach the minimum participation level.

Dying doesn't necessarily prevent you from getting the credit. However, going too long without participating in the fight can cause you to miss the credit.

For bosses that are not part of the cooperative loot system, a single hit is enough to secure the credit, provided the boss doesn't take too long to die.

Answer 2

For participation bosses (nemesis bosses), you are required to take damage. Dealing minimum 1 damage will always be enough as long as you arrive to the fight on time, and ensure you took some damage. If you attack the boss and leave, the boss needs to die within 300 seconds (5 minutes) of your attack in order for you to get the bosstiary entry. If more than 5 minutes have passed, you need to attack it once again.

If you mean lever bosses, dealing damage is the main factor to getting the tag. There is no exact "minimum requirement" that Cipsoft have confirmed, but personally on Rotten Blood bosses, I have gone in, thrown 4-5 runes and left the teleport to ensure both the loot and bosstiary entry