Adaptive Strike
The damage condition is based on Morphling. If Morphling has 50% more strength it's 25%, if morph has 50% more agility it's 50/100/150/200%. The agility used to calculate the damage however is from the reflecting hero.
Toss and Growth/Aghs
Reflected Toss will never include the increased damage from Growth or Aghs
Soul Assumption
Soul Assumption is always reflected with 0 Souls, so 20 damage.
Unstable Concoction
Unstable concoction works fine and deals damage as if the reflected skill was brewed for the same time.
Lvl? Death
Works perfectly.
Soul Rip
Works fine
Reaper's Scythe
Works and triggers the increased respawn timer and the kill is credited properly.
Test of Faith
Reflects the spell with a new random damage value.
Chaos Bolt
Reflects the spell with a new random damage and stun value.
Culling Blade
Works properly and triggers the kill condition.
Stifling Dagger
Can't crit.

Dagger and Toss probably make sense because the reflecting hero simply doesn't have the passive/item. Soul Assumption is probably the same thing (the reflecting hero doesn't have the skill, so no Souls). However, at the same time Unstable Concoction deals proper damage without brewing and Soul Rip also deals the damage dealt, not the damage that it should do based on allied units around him (EDIT: Stupid me, Soul Rip also counts enemies, so it's fine). Adaptive Strike doesn't make sense at all and seems bugged.