[C] Several melee/range differentiating spells check for range type at the wrong time

[bu3ny]

The following items and spells check for range type (melee or ranged) upon projectile impact, instead of projectile launch:

1. Battle Fury
2. Empower
3. Echo Sabre
4. Orb of Venom
5. Vladmir's Offering
6. Diffusal Blade

And the following properly checks for range type upon projectile launch:

1. Eye of Skadi
2. Quelling Blade + upgrades (Quell)


Repro:
1. Pick Troll Warlord and level up Berserker's Rage
2. Based on what you want to test chose one of the following:
2.1. Buy Battle Fury and place some creeps in front of you
2.2. Create an allied Magnus and level up Empower and place some creeps in front of you
2.3. Buy Vladmir's Offering and lose some health
2.4. Buy Echo Sabre
2.5. Buy Orb of Venom
2.6. Buy Diffusal Blade, create an allied Morphling, get Aghanim's Scepter on him and create a Hybrid illusion of Troll Warlord
3. Be in ranged form
4. Attack an enemy
5. While the projectile is flying, switch to melee

Result:
1. Battle Fury: Applies cleave in front of you, despite the proccing attack being a ranged projectile
2. Empower: Applies cleave in front of you, despite the proccing attack being a ranged projectile
3. Vladmir's Offering: Lifesteal heals for 15% melee, instead of the 10% ranged value
4. Echo Sabre: Procs, giving attack speed and slowing the target despite the proccing attack being a ranged projectile
5. Orb of Venom: Slow uses 12% melee value, instead of 4% ranged value
6. Diffusal Blade: Burns 20 mana melee value, instead of 10 mana ranged value

Expected: All of them should check for the attacker's range type upon projectile launch, not impact. A ranged attack projectile should never be able to apply melee effects.


This is partly abusable, especially for the slowing effects. Like with Orb of Venom, Troll Warlord can basically always use the 12% melee slow even when in ranged, by simply switching once before the attack lands and then refreshing the 12% slow. Sabre and Cleave can be abused in the same way.

(forgot to add orb of venom in the video)

[psioniC]

The miss chance when attacking a unit at a higher elevation also is checked upon projectile impact instead of projectile launch. This results in units standing on the high ground and then running to a lower elevation before the attack projectile hits them, losing the chance to evade an attack and vice versa. It also physically makes more sense to be determined whether a ranged attack is going to hit or miss at the moment the attacker is aiming and launching the projectile at a unit standing at a higher elevation, and not after it is already launched. This miss chance property shouldn't change in betweeen mid-air.