He looks considerable bigger than Large size in that picture!
For that matter, the picture gives no indication he has four arms like the Slayer Genie you've based the stats on.
If I were to use that card as inspiration for a genie, I'd go for one with size changing powers - either the ability to grow to gargantuan size, or maybe the ability to shrink a grappled victim to the size of a doll.
Maybe add greater teleport to any area that's in darkness, to go with the flavour text?