The idea with this build is to get a lot of passive damage going while focusing on one damage skill. All of your skills will be working for you at once. Use zombie dogs and gargantuan as a meat shield. The dogs will last longer with healing and the gargantun will help mow down multiple enemies that might otherwise overwhelm the meat shield. Next lay down huge toad and spider queen while the enemies gnaw on your meat shield. These two abilities will be doing constant damage without needing be recast for at least 22 seconds. The toad will take one enemy out of play while dealing single target DPS while the spider queen is pumping out AOE damage. After that bust out three haunts that will get some good mana regen going while you spam auto target firebats. If you want you can change firebats to a crimson rune for more damage. Refresh spider queen as needed. Passives would be Vermin to enhance Toads, Bats, and Spiders. Zombie Handler for meatier zombies and garguntan, plus the extra dog. Finally Fierce Loyalty if your gear configuration makes it worth while otherwise use another passive that would best augment your build.
Summon Zombie Dogs - Alabaster Runestone
Your zombie dogs gain 65% of damage dealt as Life, half of which heals you.
Gargantuan - Indigo Runestone
Gargantuan gains a Cleave ability allowing its attacks to hit multiple targets for 210% of your weapon damage as Physical.
Plague of Toads - Obsidian Runestone
Toad of Hugeness
Summon a giant toad that swallows enemies whole for up to 5 seconds, digesting for 90% of your weapon damage per second as Physical.This rune adds a 5 second cooldown to the skill.
Corpse Spiders - Indigo Runestone
Summon a mother spider that births spiderlings dealing 103% weapon damage per second as Poison to enemies in the area. Lasts 22 seconds.You may only have one mother spider summoned at a time.
Firebats - Indigo Runestone
Rapidly summon bats to seek out nearby targets for 210% weapon damage per second as Fire.
Haunt - Golden Runestone
The spirit returns 100% of damage done as Mana for you.