Cok Testing

minnt

Testing done on dragon "Palhavorithyn and Valindra" at the beginning of the trail.

Dragon Slayer Overload does not work.
Undead Slayer Overload does not work.
Dragon Slayer Potion does not work.
Wondrous Dragon Belt Item does not work (i only tested the rare quality).

Red Eye's Stare ring's 10% additive dmg agains undead works.
Boon 5% additive dmg to undead works.

minnt

On further testing it seems like Undead Slayer Overload does not work on any undead mob. So "Palhavorithyn and Valindra" is probably just marked as undead and not as dragon, that would explain the results.

sergey235711

I used machine translation:

The following works vs valindra on the dragon (1 boss) and vs valindra:
Slayer and protection marks against undead;
Boons with damage bonus against undead;
Rings with damage bonus against undead;

The following doesn't work vs valindra on the dragon (1 boss) and vs valindra:
Slayer and protection marks against dragons;
Dragon Slayer Potions (both types);
Scrolls of protection from dragons (both types);
Bahamut claw;
Bahamut scale;

The following works vs dragon:
Slayer and protection marks against the undead and dragons;
Dragon Slayer Potions (both types);
Scrolls of protection from dragons (both types);
Bahamut claw;
Bahamut scale;
Boons with damage bonus against undead;
Rings with damage bonus against undead;

*Bahamut scales have 1 second cooldown and do not stack;
*Bahamut claws stack;
*Undead slayer mark rank 2 is broken and doesn't work at all;
*Marks of protection aplly damage reduction debuff on enemies for 5 seconds, when you receive damage;
*Damage reduction from undead boon doesn't work;