About farming 2* Rainbow Evo Runes

[osiris0000]

As a mid-level player, i have dozens of 3* talismans which are waiting to be 4*. Since leveling up a char is a pain in the neck, i have decided to level my talismans on the way instead of focusing level-up chars,so then i will have more powerful team with 4* talismans to farm and go further. I am trying to farm different locations but it takes so long time. Where do you farm your 2* rainbow evo runes, which place is the highest drop rates for 2* rainbow evo runes? Any experience will be appreciated.