Lane bullying and mana sustain
Improved attacks and sustained damage
Attacking a champion 3 times will expose them, dealing bonus damage and causing them to take more damage from all sources for 6 seconds.
Takedowns restore 20% of your maximum mana and refund 10% of your ultimate's cooldown.
Takedowns on enemies grant permanent Tenacity.
Deal more damage to champion with more maximum health than you.
9% attack speed, 10 ability power or 6 attack damage
Gain 10% CDR when you reach level 10. Excess CDR becomes AP or AD, Adaptive.
Hitting enemy champions with a spell grants maximum mana.
After reaching 250 mana, Manaflow Band restores 1% of your missing mana every 5 seconds.
With the use of his [W] Jayce is easily able to quickly proc the bonus damage and empower the rest of his combo.
The combination of Presence of Mind and Manaflow Band relieve you of having to delay your damage by purchasing a tear for Mana sustain.
Jayce's biggest weakness is Crowd Control. Legend: Tenacity paired with Mercury Treads means you should be able to escape most ganks with relative safety.
Jayce excels in matchups into tanks where he can abuse his ranged kit. Cut Down brings some extra damage to kill those tanks.
As a form-swapping champion, Jayce's damage comes from repeated casts of his abilities so CDR is a must have.
Combined with Presence of Mind, you should have little issues with mana sustain while still being able to harass your opponent with abilities.