Path of Exile

Players can have a maximum of 12 zombies at once:

3 from the skill gem
5 from passive skills
3 from unique items (wearing Bones of Ullr and dual wielding Midnight Bargain)
1 from a body armour with Catarina's mod
2 from Eyes of the Greatwolf

see link:
https://pathofexile.gamepedia.com/Raise_Zombie

Here is a link to show the 5 passive skills map
http://www.pathofexile.com/passive-skill-tree/3.0.1/AAAABAMA...

From the POE Wiki as of Sentinel League 3.18: https://www.poewiki.net/wiki/Raise_Zombie

Players can have a maximum of 18 (19 if using talisman, 20 or more with legacy items and/or specific str-stacking build ) zombies at once:

• 6 from the level 20 skill gem (up to 8 zombies from level 34 gems, but not practical to reach such gem level)

• 2 from passive skills

• 1 from a body armour

• 1 from Jun's veiled mod on helmet

• 1 from amulet (2 from Eyes of the Greatwolf that has the correct implicit +1 to maximum number of Raised Zombies, which would be doubled due to Eyes of the Greatwolf's explicit mod; or specially crafted talisman listed above)

• 2 from dual wielding Midnight Bargain

• 5 from The Baron with 2500 Strength (1 zombie for 500 Strength unless using legacy item; 3000 Strength may be reached by some build)