Resources
This essay is listed in my "Master List of Essay Threads" under the title "On Why Champs Have Specific Resource Types"
They don't exist so that champs 'have something to manage', they are there purely because designers want certain champs to play a certain way.
Did designers intend for you to spam the shit out of powerful spells mid-late game, but not want you to be a lane bully? You get mana.
Did designers not want for you to be able to itemize for increased spell spam via cdr/mana/mana regen, but also don't want you to run out of mana in lane? You get energy.
Did designers want you to spam spells literally whenever you find an opportunity where it makes sense to, with the desire to have you be limited in some other way such as damage, cooldowns, or squishiness while being melee? You get 'no resource'.
Did designers want you to be super aggressive and make you weaker when you aren't being aggressive while also never running out of mana? You get rage.
Did designers want you to carefully balance your ability rotations to optimize damage with a significant risk for over spamming, without running out of mana? You get heat.
Did designers want you to be constantly on the move, spamming skills and dashing around, while being vulnerable if you ever stop moving, and without worrying about mana because you need to spam constantly to survive? You get flow.
Etc.
It's not about how 'fair it is' for one champ to have mana and another champ to have energy/fury/rage/heat/no resource. It's about how the designers want the champion to play.
Lux has long cds and mana because she has the longest range of almost any champion and would bully everyone in lane otherwise - and she's not intended to be a lane bully.
Renekton is intended to be a lane bully, so he uses no mana and in fact gets stronger specifically by pushing lane.
Zed has energy because he would be worthless mid against any ranged champions as a melee squishy if he went oom from using shadows and shurikens to farm, but they also want him to only be able to assassinate one person late game before running out of resources.
Katarina has no resource because her entire kit is designed around being useless unless she can start resetting her skills and going on a reset spree - and running oom when her time finally comes to shine would be dumb on top of her shitty lane phase as a melee with low damage, high cooldown skills and an interuptable point blank ult.
