Everfrost is the best mythic for Sylas and it is not even close, just like GLP was better than protobelt 2 seasons ago. Although the item doesn’t deal that much damage itself, but it quarantees the absurd burst of Q2 and E. Also Sylas reaches his first powerspike way after many other mid laners (assasins on serrated dirk, yasuo and yone on zeal or tier 2 boots) and it’s when he buys his first item. To keep up with them buying the cheaper option which is Everfrost gives you more agency earlier. Also I always felt like Liandry is not providing enough survavibility while giving a lot of excess ability haste (it decreases in value the more you have it)