Two Worlds II

I was able to complete the 4 maps solo and I didn't need a million gold to do it and was able to clear the encounters. I started at about lvl 30 with 60K gold and finished at lvl 39. Here's the build I used:

2 Handed polearm warrior - I used wieldy naganita for most encounters but any long polearm should work. You also want a 2 handed blunt weapon for dealing with slash resistant monsters (stone sentinels, necris, tailer, golems, etc)

Skills - Most important to max out are radial barage, retribution, defensive stance, elemental resistance, resilience, poison resistance and physical resistance.

Attributes - Strength is most important followed by endurance. I had about a 2 - 1 ratio between the two. I didn't put any points in accuracy or willpower

Tactics - run up to a group of enemies and do a radial barrage. Go into defensive stance and do a normal swing until RB recharges then spam it again. While in a defensive stance you will also get occasional barrage swipes from the retribution skill. If there are mages or archers on the field always go for them first to interrupt their spells/ranged attacks. If you get hurt either use a healing potion or run away and recharge naturally. You can also use the endurance/strength/willpower/accuracy altars and they will heal you fully. So if you see one while you are exploring it's usually better to pass it by and wait until you are hurt to use it rather than take a boost in a stat that won't help any i.e. willpower/accuracy. There are several encounters with multiple mage/archer types that you have to employ a hit and run technique, i.e. run up to one of the mages, unleash a barrage then run away until it recharges. If you stand in one place you will get hit by multiple spells/arrows and die quickly

Note that this build also got me through the main game adventure mode solo without much difficulty. All and all I was a bit disappointed in the DLC maps probably not worth the points but you can also get the maps with the GOTY and Velvet editions of the game. I was hoping for some good loot and some good maps to level on but didn't come away with much, I was still swinging the same weapon that I started with at the end of the 4 maps, I didn't find anything better. There also doesn't seem to be anyone online playing with these maps while it's pretty easy to find a party to run with on the main game adventure maps.

I obtained this achievement absolutely SOLO. Went through all 4 maps with just me playing alone in Adventure mode. Run through most mobs to speed it up. Still took me several hours. The Underground map was horrible, be sure to look for hidden switches everywhere. I used a level 36 character. If you do this alone, prepare to die A LOT, and have 1 million gold ready to spend on health potions and armor/weapon upgrades. The shopkeepers respawn their inventory almost instantly after you for example, buy all the health potions, then have more in under a minute. I did not buy the DLC, but rather bough the Velvet GOTY edition from Amazon which included this achievement (4 maps) as well as the Pirates expansion. This guide is mainly to let people know it can be done solo (no one plays online on these maps!!) and that they don't have to buy the DLC, just get the GOTY editon, no codes needed! If anyone needs 1 million gold to buy all the potions needed to do this solo, send me a message and I may be able to help you, as I have 8 million left. Do not contact me unless you are planning to get the achievement solo and need the gold.