its not a bad build but the issue with it is that you cant really box for quite a while, becuase not only does transcendence cost an arm and a leg, but you are then following it up with warriors instead of ninja tabi. Eventually you do get asi but the extra lifesteal on low health wont really matter bc the top adcs (cupid and artemis) can just burst/stun you so you cant utilize it. Not listing xbalanque bc giving the hardest hitting adc in the game a free pass through the early game will ruin your game anyways.

The only reason that I would actually support this build is because of hou yi's passive negating most of the crits whenever you do box another adc. On ullr this doesnt exsist so I'd just say stick to the meta build because its a waste to handicap ullr's strong laning with a build that will make him significantly weaker early game.

Also now that hunters are super strong late game the old unicorn build isnt as effective because you can just crit them down just as fast with a build that will actually kill a squishy in 3 shots rather then a 5-6 build based around killing tanks.

I also dont like Ichaival in general (but that's just personal feel), I just prefer executioner since it gives the same power as a full stack ichaival, the same penetration, BUT 15% more attack speed. So not only are you doing more at the start of a fight, but you also will attack faster before the ichaival even has time to take effect. Also that one full power crit early from a god going meta build will probably win any trade because any power negation the ichaival does from there cant out dmg the crit at full power (taking the hou yi passive into account here).

Deaths toll is a fine item still but early dev gloves and bluestone are just flat better instead of deaths toll and transcendence. Dev gloves are 600g cheaper, bluestone gives the same mp5 as transcendence so the only thing you lose is the larger mana pool, and dev gloves actually allow you to solo GF quite early (Ullr could get away without them from the passive lifesteal in axe mode, but you dont want to rely on axes in a team fight).

TL:DR On Hou yi, sure go crazy, on Ullr probably better off sticking to the meta for now. (and fuck ichaival >_>)