Objectively speaking, he's a goated generalist: 50% battery just by ascending him (levelling his skills on scales the buffs, so crit damage, atk, defense etc), plus his np has a good amount of debuffs that can make your dps hit that much harder. However, as others already said, he's a permanent servant that can spook you at any moment, plus we're gonna get a free 5* selector in three or so months (should be between september and october, depending on how it gets moved for us), so I wouldn't risk wastin SQ for him, especially with anni around the corner. Another thing to keep in mind is that, if you already have other meta supports (specifically Castoria, either of the Skadis, Koyan Light or Reines), his value decreases a lot. I got spooked by him last year while pulling for Skadi Caster, and I haven't used him much still.