I suggest a new mode: Super Crucible of fire!
It's similar to normal Cof, but you CAN'T retreat battles, the enemy party start with NO energy (bye bye hurok), and it consists of 20 battles instead of 15. Therefore, there is a new shop, in which you can buy some soulstones of recent box hero event or conjuring stone hero, but lot price is 2000 instead of 500. The final battle GUARANTEED a hero card, but this battle must be almost impossible.
Is this a good idea?