Note before we start know that people dislike the use of summoners, and will likely be kick from most groups at high level, unless playing with friends of course. Until the fix particle spamming.
Raise Spectre - Numbered in ordered of what to get first.
(3)Greater Multiple Projectiles
(4)Added Chaos Damage
(5)-(6) Once you find a 5L-6L chest of course!
Chain(good but less damage)
Faster Casting(good for casting mobs)
Faster Attacks(good for projectile mobs)
Lesser Multiple Projectiles(good but less damage)
Elemental Proliferation(increased Damage)
Item Rarity(stacks with your own)
These are your damage. Getting the right spectres is EXTREAMELY important. i use the minions at Solaris Temple Level 3 they are called Flame Sentinel. I am also a big fan of getting the range mobs in Lunaris level 2-3 i forget what they are called but they fire 1 projectile from each hand. So they fire 8 projectile every .3 sec(INSANE). alot harder to get thou.
-Tip press A when summoning a spectre to select the right one.
Raise Zombie - Numbered in ordered of what to get first.
(4)Melee Physical Damage
Next you want personal guards to tank Bosses/Mobs that want to get to you, best scaling hp in the game. Currently mine have 9.6k hp each (x10 of them), which is insane when you have minion instability which deals 30% of total life when it dies(big dps).
Raise Skeleton - Numbered in ordered of what to get first.
I also have raise Skeleton which are attached to a totem and the Skeletons swarmed the boss so he cant move, while your spectres kill them. Really good trick while dealing with boss such as Brutes etc.
Secondly you should be running auras and curses to assist your undead. Purity, Discipline, Warlords Mark, Flammability, Elemental Weakness.
Currently level 67 and have:
Unique Minion Amulet.
Unique Minion Shoes.
Unique Minion Wand.
A side note i should is that for your health flasks you should try to get "Grants 57% of life recovery to minions" keep rolling for it until you do, though the highest flask is 960 so you need to spam the flask to keep them up in boss fights.
57% of 960 = 547.2
9600 / 547.2 = 17.5 Times to heal a zombie to max hp.
Overview: use spectres to kill, use zombie/Skeleton to be a meat shield and tank the boss to death. Also soloed Piety on cruel. Brutes took me less than 1 min on Merciless solo.
Skill Tree(Still have somethings to refine)