Namahage has the special ability the red head he receives attacker receives +45 and for every hit he gets extra. But if you have an other hero giving extra attack buff than his special ability is removed. So you cannot have 25+ attack and his ability. I think this is a bug… I played with a red team with zimkitha and boldtusk…
Also its strange that when you have boldtusk 48+ and you attack with zimkitha you lose the 48+ and only have the 25+ attack.
It is logical. Otherwise the buffs would be too powerful.
There are however some exceptions:
Wu Kong and Ranvir stack with other attack buffs
Miki stacks with other attack buffs but only up to +170% attack in total
Tarlak stacks with other attack buffs but only up to +160% attack in total
Also Miki and Tarlak buff only normal damage, their buffs don’t apply to special skills.