Some of these challenges are nearly impossible to get done... especially if they're dailies.
Finishing Moves = People rage quit during or before the animation even starts so it doesn't count.
Location Knockdowns/Kills = Tons of areas are flat out ignored by the community entirely because they're "too far."
Care Package Weapon Damage/Kills = High risk/little reward to go after them in the wild on top of dealing with brutal RNG odds. Only way to farm them is playing Lifeline then praying you get a weapon to drop and hope you loot it before your teammates do.
I'm not even going to get into the multiple kill/knockdown in a single game challenges that only award 6k XP instead of an entire BP level. I'm fine with difficult challenges but most of them aren't worth the trouble and since you can't reroll them you have no choice but to ignore them.
Any word on future tweaks to them?
