Celerity unfairly biases in favor of AD
Celerity (Tier 3 Sorcery) Gain 4% increased movement speed and add 8% of your bonus movement speed to your AP or AD, adaptive
AD is worth much more gold per value, yet the rune gives the same bonus to either stat.
In fact, per unit, AP is only worth about 62% of AD in gold value. In order for Celerity to give a compatible value for AP as for AD, it would have to add 12.9% of your bonus movment speed to AP or 8% to AD, adaptive.
items give movespeed and so does
,
,
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(i know its only on its active but its still there) while ap is stuck with a ludens or lichbane