1. What is there to explain? Orb effects are special 'on hit' effects that do not stack between each other. They may or may not place buffs (two buffs can not be placed on a single attack). Common orb effects:
Non-aura lifesteal (Mask of Death, Frostmourne)
Orb of slow/frost/lightning/fire abilities
Searing Arrows, Cold Arrows, 'Poison Arrows', Black Arrow
Some non-orb abilities that can give similar 'on hit' bonuses:
Frost Breath (ranged only)
Vampiric Aura (melee only)
Slow Poison, Envenomed Spears
2. Evasion does not stack. It appears that the ability with the largest evasion bonus will override the others.
Bash does stack, both separate and same bash abilities will stack. Two bashes can not go off on one hit.
Crit does stack in the same way as bash. You can not get a "double crit", one will override the other (not necessarily the highest damage either).
1. Extending TheDamien's post, the non-orb abilities like Frost Breath and Slow Poison are buff placers, meaning that they cannot stack with other buff placers. Buff placers are skills that inflict a status on a target, like Frost Arrows. So that means Frost Breath and Frost Arrows will not stack. Note that many triggered orb effects use buff placers to detect when the projectile hits the target so most triggered orbs are also buff placers.
2. Bashes and critical strikes stack diminishingly; meaning that when both go off, only one can happen. In melee when two Bashes happen at once, the bash damage stacks but the length of the stun doesn't. In range, only one Bash happens period. In crits, whichever critical strike skill you obtained latest will happen when both crits go off.
http://forums.battle.net/thread.htm...pp23_04?topicId=14637465039&sid=3000&pageNo=1
this is a post in battlenet forum regarding pseudo-random distribution in wc3 used in bashes, critical chances
not the actual main informative post, its there somewhere in the forum, its also in dota forum
basically 15% bash chance is not actually 15% in wc3 and also have weird effects on stacking behavior
i am not too sure if it affects evasion too
With critical strike you can get 2 criticals at one time and the damage from both will be dealt, when it is said a critical strike will not stack what is ment is that they will not stack on each other, in other words this wont happen
base (10) x critical 1 (2) = 20 x critical 2 (3) = 60
Instead this is what you get
(Base (10) x Critical 1 (2)) + (Base (10) x Critical (3)) = 50
Ghan has said he has fixed this. Monovertex please confirm this fix. This was only a problem with people that had signatures in the upper levels like not the special members but the respected members.