Zombie Modifier

Besides having upgraded types of zombies, SAS4 zombies can have buffs too.
 * Fiery Skin: 75% thermal resistance, +100% fire damage.
 * Poisoned limbs: 75% poison/acid resistance, 100% acid damage over 3 sec.
 * Chitinous Hide: 75% physical resistance.
 * Extra Fast: +50% movement speed.
 * Berserk: 3X attack speed.
 * Extra Strong: 2X damage on all attack(including fire, toxic/acid).
 * Regenerating: +5% health/sec.
 * Energy Resilent: 75% energy resistance
 * Dark Minion: functions like Shadow in SAS3, ignores obstacles, ignores armor(only heavy class can reduce damage by using Tough Body).
 * Acid Blood: creates a puddle of acid that lasts 10 sec. on death. On contact with the acid, 150% damage over 3 sec. The acid lasts 3 sec. after getting out of the puddle.

Combinations
After June 17, 2014 update, each zombie type has 2 types of elites with set combination of buffs(used to be random buffs on everything). Now, the bosses have buffs too(only Berserk, Extra Strong, and Extra Fast). Some of the op combos:
 * Bloater+extra strong or dark minion(1 hit kill), +acid blood for trolling.
 * Any zombie with all resistance + regen.
 * Anything not shamber with Extra Strong + Berserk (6X dps)