what keystone would you use for singed

idk i saw this guy who had 600k singed mastery use fervor in all his game though. maybe it was an accident though honestly though DFT is probably the best on him. that or stormraider's surge

he doesn't need one

Probably best to go with grasp of the undying, with the amount of health he ends up with it increases his survivability and damage by quite a bit, allowing him to be even more annoying.

i would say strength of the ages or grasp of the undying