What level of stacking is possible with at-will modifying feats?
Take, for example, the fighter power: "Cleave"
At-Will Martial, Weapon
Standard Action Melee weapon
Targets: One creature
Attack: Strength vs. AC
Hit: 1[W] + Strength modifier damage, and an enemy adjacent to you other than the target takes damage equal to your Strength modifier.
Cruel Cut Style (Feat):
Cleave (fighter): If no other enemies are adjacent to the target when you hit the target with this exploit, the target takes ongoing damage equal to your Wisdom modifier (save ends).
Deft Hurler:
Cleave: You can forgo dealing damage to the adjacent enemy to instead make a ranged basic attack with a heavy thrown weapon against one creature other than the target of your cleave. This ranged basic attack does not provoke opportunity attacks.
Criterion of Balic Practice:
When you use a power associated with this feat and hit an enemy with it, you can shift 1 square, or 2 squares if you are an elf. The shift is a free action, and you ignore difficult terrain during it.
and
Longhand Student:
If you are attacking with a two-handed polearm or a two-handed spear and you have proficiency with that weapon, you also gain the following benefit.
When you hit an enemy with a power associated with this feat, you can push that enemy 1 square.
Without recourse to other rules, all four of these feats are technically compatible with a farbond spellblade glaive. (Note that using all of these at the same time is silly but that's beyond the point.) If all of these are applicable at the same time, what order can or should they be resolved in?
Best Answer
Beyond the points that Acedrummer_CLB exquisitely exposed, I think that in every occasion you could apply more than one effect under the same conditions and these effects come from different sources (powers, feats, whatever), you could apply them in the order you prefer.
I think, however, that the effects of all four feats in the example should fall under the hit or miss phase (they all apply only on a successful hit only).
Under this hypothesis while the decision to exploit the Deft Hurler option takes place before the attack, its effects, Cruel Cut Style, Longhand Student and Criterion of Balic Practice effects could all take place in the hit or miss phase.
These four effect are not simultaneous, but could be applied in any order. A possible sequence of play could be:
I have found no reference to rules that prohibit the appliance of multiple "at-will attack modifier" effects. A more formal at-will attack modifier definition or keyword may be needed.
However, as the number of publish material grows, some at-will attacks could become far more powerful than many encouter attacks.
I'd house rule that no more than one "at-will attack modifier" feat could be applied on a single power utilization; and this decision must be made in the before the attack phase.