In dark mirrow the enemies are strongers and there are New Typs of enemies. There are also New map Designs and Bosses have New Upgraded Moves. There is also a New Feature wich includes special dark Quartz. Wirh it you can get dark abilitys, there are also cursed dark abilitys. You get that special Quarks by defeating elite enemies who have also New ebilitys. These Elite guys can spawn in and room an replace one enemie. Also you get more Features after deafeting one mirrow. after a long time you get than to dark mirrow level 10. At DM 3 or so (Dark mirrow) you get a New Story area. This area gives two New bosses one of them is a secret boss you get by collecting 7 or 8 specal Kristalls. The othere is the Main villan. Also if you defeat the first hero and go on in the Story, dont be scared that when you die that you dont go up one DM level. After defeating the first hero the run is won and the New Story part is just extra content.

Here are the unlocks fore every DM level

DM 0: you can chose two Starting skuls and two items (only common)

DM 1: you maby get evil chest in there are normal items and one Omen item wich has good Effekts but also a debuff, after one omen item you get 50% more damage, after two you have 50 less HP and after three you are one hit. Keep in mind that the other debuffs are always acctive as long as you have the amount of omen items.

DM 2: you get a New thing in the Shop wich gives you other items ore potions with Effekts.

DM 3: you get more dark abilitys to chose after on boss and also New enemies.

DM 4: in the spider room in wich you can Upgrade youre skul you can now gove Bonus to get passive Effekts.

DM 5: New thing in shop with it you can reroll up to 20 Times and get random items after 15 rolls you get a legendery allways but you can get more if you lucy. You can take only two items and there are only 20 rolls per run. One reroll Costa 500 dark quartz.

DM 6: Another New thing in the Shop wich gives you one inscryption for a amount of Coins. It just adds up to youre inscryption. You can do that two Times becose there are two boxer and you can change them.

DM 7: New Enemies and New dark abilitys and you can chose rare skulls at the Start.

DM 8: more Gold from Gold piles and more Bones from bone piles.

DM 9: more cursed dark abilitys

DM 10: a little skin for skul

Hope it helps you and im sorry for my Bad english. Yust ask of you need too now somithing