Spirit Hunters: Infinite Horde

I got this redoing the hard maps because my Achievement for beating all hard maps glitched (its not totally glitched. see the achievement guide) This isn't nearly as hard as it seems. On most maps you can get to around level 60ish without much effort. There is a Challenge that starts Vivian with the Cici and Mag Slime Pets. It might be helpful, but it does limit you to using some abilities. Doing this on Brutal will also help as new enemies give more souls. I got to level 90 on a Brutal Desert Ruins with not much effort. There is many ways to do this but, here's how I did it:

I did this on the Hinterlands map on hard. I used Vivian with the Arrows as my starting ability. I love the arrows and with Vivian every arrow kill gets you a blue soul. Starting out this will get you some quick levels. Vivian also gets increased loot Magnet with each level. I also used The Bones, The Shuriken and The Electric. The bones hit hard and will cover your top and bottom. The shuriken's will cover many directions and when you upgrade it to star shot it will kill a lot all around you. The Shock is really good for crowd control and kills a lot all around you also. I like to upgrade the cooldowns on arrows and bone to 5 ASAP and go for the range on the bones so it will go the length of the top and bottom of the screen pretty much. Then i work on Critical hits for those 2. I also go for cooldown and area on the shock and the number of shuriken's and critical % on them also. After you get those leveled up then go for MultiShot on the arrows as every kill with them will drop a blue soul at least. Then go for splinter and impale or Start Shot with the Shuriken's. I didn't use the Turret Shock mod but i did use Chain Lightning. Your getting 25 levels in each ability so just get whats best for you also. This is just what i went for. Here's the pets i used.

First off you wanna quickly get gold as fast as possible so when you hit a Pet box you can reroll. You will also need gold to buy pets at the shop after you get them. You can also buy these pets if you don't already have them if they are available at the shop. I went for these pets in this order. The first 2 you can really get 1st or 2nd. just get them quickly.

Cici - Increases blue Soul Value in 10% increments up too 100%
Mag Slime - With Vivian's loot magnet increase every level and this pet your magnet will get souls you wont even see.
Flash - Vivian is already fast this makes her way faster to move around and let Mag Slime do its job collecting souls and letting Cici increase them.
Lock Pick - just to make chest opening faster to get more and more gold for the shop. After you get your pets leveled then always buy the blue souls at the shop.
Big Tex - this slot don't really matter i just picked Tex cause he makes the weapons larger to have an increased hit range.

Just move around the level and kill everything and once you get some upgrades going and get the pets going you will notice the increase. I also passed on opening the mining spots on the map to help get levels faster. Not sure if this helped much. I was past level 50 before the halfway 7:30 Mark. I had about 1 minute left when I hit 100. The achievement pops in game so you will see it right when you hit level 100.