Instead of trying to do protection from bad RNG, they could always just get rid of the bad results... Like while wasn't well received when everyone of the 6 major cards was just a DPS buff, it did mean you could always use all 6 of them regardless of what you drew into.

Now, they don't all NEED to just be "Increase damage dealt by x%", but you can have other flavors of increasing damage such as Crit, Direct Hit or Haste buffs... And Lady of Crowns being a nearly useless heal could very well replaced with just another attack like Lord of Crowns...