Buff/Debuff Overwrite Suggestion

[Ardox]

That sounds a little too easy and 'hand-holding'. There'd basically be no penalty to improper timing.

One thing they could do, is allow buffs like that to form stacks, but have successive stacks have diminishing returns.
1 stack of Trick attack gives a 10% debuff.
2 stacks of Trick attack give a 15% debuff.

This way, it certainly wouldn't be worth having two Ninja's, but if you did, and their buffs overlapped, it wouldn't be wasted, but there's still incentive to time them apart.

Most classes have burst phases and having a stackable debuff would be less punishing than having an extended debuff in my opinion..

In both case, you'll lose some efficiency anyway (either the buff is so long everyone had time to do their burst phase and are now back to their standard rotation or you get a slightly bigger debuff to use your burst on..)

Problem with upgrading the buff (10% to 15%) is: what will be that debuff duration? It's easy to implement +10 seconds to TA, it's less clear how your proposal will work. What happens if NIN2 use his TA at the 9th second of NIN1's TA? Do we now get another 10 sec of a 15% debuff? Do we get 1 sec of 15%? Something in between?