Sure, it has troll capabilities, but it's truly not that bad. From what I gather, he's meant to be a support, and that ability can be really useful for saving an adc from a rather risky play. Not to mention the ally can choose when to get out.
I can imagine he's meant to be more of a tanky support. While his melee attacking would make Relic Shield an optimal start, I'm guessing he'd probably rather have talisman for escape and catch potential combined with his W. Additionally, Righteous Glory and Randuins Omen will probably be optimal; Righteous Glory for the pick potential and the health scaling passively with his ult; and Randuin's Omen for the additional pick potential, allowing him to stick to his enemies to apply stacks of his passive, nice resistances, and the health to scale with his ult. Also add the obligator Mobi/Lucidity Boots and a Sightstone/Ruby Sightstone, and you're left with one item slot that I would probably use for a Locket of the Iron Solari.
It looks as if his ult also has enough range to go from top to mid in the video, so I can imagine his mid roam potential with his adc after picking off the bot lane is impeccable, as well as being able to get to global objectives faster with an ally. In my opinion, his E is very necessary considering he does have to get relatively close to his lane opponents to apply stacks of his passive for the stun. Hs extreme bulk will allow him to be a nuisance in team fights while still being able to apply passive stacks where necessary. Although he could probably succeed top lane, or even possibly the jungle, I feel as if he just has a lot of synergy with high cc comps, so leaving top and jungle to high cc champions such as Gnar and Sejuani is just more useful. Very eager to try him out on the PBE when I can.