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Complete the quests
Every game has some quests for which you will receive Soul Gems.
You can exchange your Soul Gems for Steam Wallet top-ups, game keys, CS:GO Skins and other rewards.
You'll get 1 void shard by clearing the 12th normal campaign map and another void sharp by getting 252 stars in normal campaign ( it means you need to get 100% 3 stars in normal campaign ) . 1. Pick Kael as your starter. 2. Activate the raid card ( it's free trial for 7 days ) 3. Get your free newbie items and try your best to clear campaign as far as possible ( I normally stop at 3rd or 4th map ) 4. Keep replaying a level on the map to upgrade some minions to feed your Kael and Warmaiden ( free from clearing 1st map ) to 5* 5. Don't forget to enhance your items ( Kael has to have Blood sucker set, which can get by log in for 4 days, 1 item per day, I finished in 2 days because I use 2 low level items ) 6. Run some dungeon to get Kael to level 5 ascension ( would be better if you can also upgrade Warmaiden )Use Kael and Warmaiden to clear all the map and then get the void shards i managed to do this in 3 days with really hard grinding. so you can do it in 10< without really hard effort