hey,
I enjoy watching your videos, I just wanted to give you few tips, but it turned out to be almost A3 merc miniguide
A3 mercenaries need mostly
Faster Cast Rate (FCR) so they cast more often (58=12frames, 86=11frames, 138=10frames)
-Enemy Resistance - up to 135% for their main element
%spell damage for their element(s)
all skills
optionaly some FHR (86=8frames, 133=7frames, 232=6frames]
(they have 845 energey factor on lvl120 so there's no need for that)
Gear for bloodmage
Bloodmage uses fire (and secondary poison)
Early game I give them full honorific gear (amulet with +all skills and ideally spell damage), later I change it to Blessed Sacred Honorific - bless with corresponding shrine (fascinating for fire) + arcane crystal, even later change to full shrine crafts
Weapon : use broad or long sword - (6 sockets) - MO with 5xFCR,4x%fire damage (Ix rune is lvl 81 so there's only space for 9xMO), socket 6 Ix runes to max FCR (or 3x Ix and 3x perfect diamond for spell damage before you have enough Ix runes)
Armor : use the highest they can use/you have - MO with %ED, %fire&poison spell damage, %MF and rest FHR, socket runes with spell damage (Ral for fire)
Shield : with 6 sockets = Bone Shield (or spiked, but it has higher req, you may need use -req MO or jewel even for Bone shield), MO&sockets are same as for Armor
Misc
when you resurrect your mercenary or even when you change his equipment, he loose his buffs and became squishy until you make new game
Check
d2stats tool - it can filter "trash" items, has customizable item notifier and shows many handy stats about yout char
For resists - either MO rings/amulet or socket few gems or use jewels (can have up to 25% resist, you can get both fire&poison one one if you're lucky) - you can craft them (check
jewelcrafting docs) or even use oil of renewal on magic jewels
Before raising totems, buff yourself with bourning veil
bless you (good) crafts using shrine+arcane crystal to add shrine bonus again