Black is strong. It’s weaknesses are enchantments and artifacts. Discard mitigates those weaknesses.Where's your enchantment removal at? What was the opponent doing that they couldn't answer this for a dozen spells?
Opponent can't kill a 0/2? Crab is quite a clock, though.
Targeted and random discard steal the target's agency. I'm not personally a fan. They can make a borderline hand completely unplayable.
I'd try to look at what problems led to these unfun games. If it isn't mana screw/flood, which we're cursed to deal with, then your games should all be decent.
It becomes a problem when the answer becomes too strong. Similarly, when a lack of an answer becomes too weak. To me it seems that both of those points were valid at the same time.