If you're HARDCORE & love a challenge,  ignore this post. 
For the rest of us:
There's actually not one,  but *MANY* (Evasion) Buffs,  that can *STACK*, & make a normal enemy into a *SUPER-BOSS* -- that's how I fought & had to flee from CockRoaches!  (sp)  [had a 92 EVASION!] 
Others have had problems with them also.  
If memory serves there's actually 3 (THREE).    [3+@30 EACH=  ~90+]  They can be found HERE: 
/assets/data/        File:  Effects.gd
Be careful if you edit this to not change anything else.
For comparison: "Normal" hi Evasion: Goblins: 25
Given that they can *STACK*, I'd suggest 10 Ev each [MAX 30 stacked] ----but up to you.
[if a "normal"  -0- Ev  can have 90+,     than a Boss or already hi  Ev  enemy can easily have 110+ !!!    Maybe more.  ]
