Where in the comics does it show Dualscar's death? Or, at the least, evidence of it? (And all the rest of the ancestors?) o.o

It’s not shown, but it’s mentioned how he died here

♋, ♈, ♊, ♎, ♏, ♓

It’s very likely that the slave killed by Dualscar mentioned here was the Dolorosa

The death of the Summoner, Disciple, Darkleer and the Grand Highblood are unmentioned buy it’s likely that the Summoner was killed, the Disciple of old age, and the other two by either old age or the Vast Glub.