Then use treachery armour chance to prove fade+venom 45ias
15/15 or 40/15 jewl on guil helm
For Eth reaper toll you can socket it with shael or 40/15 if you want to reach high ias most would just use cham on guil

vouch for Guillaumes + Cham. ias means nothing if your merc is constantly slowed by cold enchanted packs or natural cold dmg. another thing to consider is what areas you plan on running. if you are going for dia/baal, your merc might be decrepified most of the time, so you might calculate for these ias breakpoints as well and adjust accordingly

I use cham guil and Ber on reaper toll for mine
55%cb
cbf
45ias
Might aura

Where do you get the 45 ias from?
Atm i put a amn rune in it so 20% ll 😁 he hasnt died tet. I do Diablo, trav, meph, baal pindle, cows

Treachery armour
5% Chance To Cast Level 15 Fade When Struck
25% Chance To Cast level 15 Venom On Striking
+2 To Assassin Skills
+45% Increased Attack Speed
+20% Faster Hit Recovery
Cold Resist +30%
50% Extra Gold From Monsters

ah sry