Why does Yorick's Q cost 25 mana
and why is there such a huge disparate between mana costs of old champs and new ones
and why is there such a huge disparate between mana costs of old champs and new ones
Because Yorick will be using it 24/7 like Nasus. If not, he'd have to get buffed hard.
Yorick's low Q cost is justified. He has to spam the skill in lane, and much of his power comes from being able to last-hit minions with the ability. It's similar to how reliant Nasus and Ryze are on their respective Qs -- and the former's costs even less mana.
Coz he needs to spam it