Why is Transcendence limited to SOLO laners?
Requiring level 10 is way too much of a burden for non-solo laners. For example, it takes jungle ~14-15 minutes to hit level 10. ADC and support are similar. Even for top it's not really viable because most top laners are melee and so they can't give up trading power for the time it takes to reach level 10.
It's basically limited to just mid and out of those, only really very safe ranged waveclear mids who can get away with it. This is way too niche and even in that highly specific scenario, it tends to be outclassed by other options. It is currently made for basically no one and isn't a great secondary either.
My proposal: make it like Magical Footwear or Conditioning. Give it at 10 minutes.