signet of vamparism problems
Well most support skills have this limitation by being a 5 man max skill. Necros are just not guarantueed of their own 20% of the cake which makes it one of the most selfless skills ever.
That is the problem with the skill and even more the trait. the healing you use to keep yourself alive is being stolen by other.
the situations the problem might occur in
scenario signet trait
wvw(zerg) no yes
wvw(small group) no yes
spvp no yes
world boss yes yes
world events no yes
raids yes yes
dungeons no yes
solo no no
world events and bosses you don’t really need traits or skills to be successful.