Leblanc's Mimic was less a decision point and more of a tool to one-shot someone with Sigil of Silence. These changes are aimed at improving the patterns and decisions around using Mimic. Our most obvious adjustment is the fact that mimicked abilities will now deal their own base damage instead of amplifying the base spell. This means players will be able to use Mimic in more creative ways at level 6, rather than holding it for Sigil of Silence. Additionally, Sigil of Silence will now deal less damage up front but more damage on detonation in order to better promote LeBlanc’s multi-skill interaction. 
Mirror Image
The Mirror Image will now attempt to run instead of standing still
Sigil of Silence
Mana Cost reduced from 70/75/80/85/90
Impact Damage decreased from 70/110/150/190/230
Impact AP Ratio decreased from 0.6
Mark Damage increased from 20/40/60/80/100
Mark AP Ratio increased from 0.3
Silence duration reduced from 2 seconds
Distortion
Cooldown now starts on cast rather than after returning to your Distortion
Ethereal Chains
Slow duration (and time until root) reduced from 2 seconds
Root duration standardized across all ranks from 1/1.3/1.6/1.9/2.2
Cooldown increased at earlier ranks from 10/10/10/10/10
Mimic
Mana Cost decreased at early levels
All mimicked abilities now deal their own base damage instead of amplifying the base spell. In all cases, the mimicked spell will deal higher damage than the base spell (due to higher base damage or higher AP ratios).