I finally finish this system today.
it's like Diablo3's Life orb system.
when you kill the creature, there's a chance to generate instant potion.
if you move to near the potion ( I set 2 tiles from the potion ), potion automatically apply to you.
there's Life/Stamina/Mana potion which gives you regenerate Hits/Stam/Mana.
also there's a buff potion which gives you stats like 2nd circle's Strength/Agility/Cunning or 3rd circle's Bless.
Regeneration potions has 5 Max level cap and buff potion has 2.
Only Damagers can see/use this potions.
if other player moves over the potion, it'll not be applied to them. (including GM / GM can see this)