Can anyone explain to me how to know exactly when the oracle triggers from smite usage and how can i make the best use of my smite to get better value from my oracle?
This is a list of the buffs you get for smiting each jungle monster
Blue Sentinel: restore a large amount of mana over 2 seconds (25% of your maximum mana).
Red Brambleback: restore a large amount of health instantly (20% of your maximum health).
Ancient Krug: for 90 seconds every 6th basic attack stuns minions and monsters. Additionally, you can attack a tower to expend the buff early - dealing a large amount of bonus true damage (65 + 15 × level).
Crimson Raptor: grant you true sight for a short duration the next time you are spotted by an enemy ward for 90 seconds.
Greater Murk Wolf: summon a rift spirit that grants sight over the nearby crossroads for 90 seconds. Whenever an enemy champion comes in range of the nature spirit, it will chase them for a short duration.
Gromp: for 90 seconds, poisons enemies who attack you, dealing 10 + (5% bonus health) magic damage over 3 seconds.
about the raptors - you get a buff that for the next 90 seconds if you step next to an enemy ward, you will recieve an oracle buff for a short duration. if you're playing low-level ranked or non-ranked games I'd suggest getting other buffs mainly and using this oracle buff to clear baron / dragon from wards