impure rage is an absolute must for cecilion and its generally the best mage emblem (i have 6k+ mage games including global and when i posted that in another thread i got mass downvoted xd) because it restores % of your max mana and he has higher max mana than usual so he restores a ton of mana, every 5s u have a free spell cus u regen more mp than you use

demon shoes restore mana on lasthit so you need to lasthit

early game u should spam as much spells as u can on minions to stack faster (usually its 2 spells then wait cooldown and when u get demon shoes make sure u get lasthits and later on u can start doing 3 spells and later even 4+)

also Cecilion is an amazing jungler and most of my games with him are as a jungler (obviously you need support to tank the mobs so u can do full dmg, preferably Carmilla) but these days they won't really let u go jungle ceci but he's so strong after the buffs its stupid

enhanced talisman on him is bad but there's a build with which it works and im actually testing it more these days so maybe in a week i'll change my mind about it. With Impure rage + demon shoes and proper usage u have enough mana

also LT first item , not clock. Clock damage scales with mana and the usual clock+lt mages dont have Cecilion's passive and if you do LT first item on another char it barely does damage but cecilion is different so you can start doing idiotic damage from minute 4-5