Riot dropping some real subtle hints in the Swain VGU Reveal
https://na.leagueoflegends.com/us/featured/champion-reveal-swain
Demonic Ascension's lengthy duration and the short cooldown on Death's Hand lend themselves toward the longer battles Swain loves, but he has trouble sticking to enemies as fights drag on. Master Swain players should opt into runes or items that offset this weakness.
drag on. Master Swain
I see you, Riot.