on Mythic 3, monsters do more damage and have a lot more HP, and on the higher floors, it only gets worse, and even more terrible when you use Challenge Maps. max out your Luck. you should have 650, 850 if you have the Fortunate Perk. the same for Gold Find if you can, as you will need lots of gold. on your Weapons, if you can, get the 100% Weapon Damage and +5,000 Weapon Damage affixes, that will boost the damage of the weapons they are on. putting Hero Points in the Skills that are on the Weapons you are using will also increase the damage. there are other affixes that can help boost damage. 20% Elemental Damage and +5,000 Elemental Damage will help the weapons that have the same Element. then there are Sets (Green Affixes). some of those can help increase Damage. increasing Critical Chance gives you a chance to do more damage, and Critical Damage increases how much damage your Critical Hits can do. Deadly Strike gives a chance for your Critical Hits to do double damage. these can help you early on, and as you put these on your Equipment, you will learn more about how to Craft your Equipment. there are other ways to increase your Damage, just look at some of the Legend Items you find, and read the descriptions to see how the affixes can boost damage. some affixes can only be found on Legend items, and some can be rolled using the Ruby Crystal. these are the Legend Affixes (the Red ones). if you have Emerald Crystals, use them to increase your Item Quality to 25%. that will increase your weapons damage, and for your other items, increase the AC. this will also make it easier to get max rolls on your affixes when you are crafting your Equipment.