I think that by making Siphon Life steal max hp and correcting the basic values of the first skill and its scaling from spirit, you can rework the first ability into a synergistic and fun skill for the hero, whose passive very much depends on his maximum hp. It is very profitable for Abrams to buy a lot of items on his hp, since infernal resilience literally screams that if player pass some kind of threshold In HP, Abrams can become immortal in a long fight. It's much more exciting fantasy to be immortal, or I would say undying as being big sponge that soaks damage and crushes enemy positional gameplay in process. Also enemies would have keep in mind that fights should end quick and build accordingly with bleeds and antiheal, or abrams will get totally out of control...