Elise's Human Form's Q Mana Cost is Literally Twice the Base Damage at Rank 1
Damage: 40 / 75 / 110 / 145 / 180 (+ 4% (+ 3% per 100 AP) of target's current health) Mana: 80 / 85 / 90 / 95 / 100
Elise's base mana: 324
Assuming the target has base health of 550 (roughly the average base health), Elise's Q's % Current Health damage comes to 17, for a whopping total of 57 damage, just 2 damage above an auto attack.
So to use her Q in human form when it's rank 1 is essentially paying a quarter of your mana for a glorified auto attack.
But really her problem is her spider form movespeed, right Riot?