Just breezed through a run as the Necromancer. I picked the wyrm as the initial spawn and while I thought that was a bad choice (I was looking at my options and somehow ended up with that one instead of the golem, which is what I intended to choose) it didn’t matter - the Necro is so strong that I pretty much breezed through the run. I had so much healing (not exactly sure from where…) that I was able to get the “didn’t use a healing potion” achieve too.
The MVP cards were two that allowed me to pay 5% of my life to invoke summons (one was a Fae and one was a Fae/Wyrm). Spawning those suckers out of nowhere was powerful, especially since the Fae heals you right back up. And I had a couple of Lich cards that stunned (one was a stun all for 2) that I would 100% use when I transformed.
So I defeated the easy last boss and hit level 20 but I didn’t get the “level 20 Necro” achievement, instead I got this one:
Which I didn’t do - although I did fight a boss who had card-stealing minions and maybe at one point they had stolen enough from me that I only had 8 cards in deck? No idea. But I definitely did not get the Necro achieve.
On to one of the above recommended guys - either Pathfinder or Wyrdhunter.