Jayce is a very versatile champion because he is able to switch from a ranged to a melee champion. This comes in very useful because you are able to harass your enemies in the cannon stance and switch to hammer stance when things get into close combat.

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For the skills you want to take shock blast to harass champions in your lane. I prefer bottom lane with this build but it can also be used in top lane. Once you get acceleration gate you can place it and shot a shock blast through it to increase damage and the distance it travels. Your hyper charge wont be too useful until later levels but lightning field will be.
This combo is very successful for me when I play. Hit a shock blast through the acceleration gate and then get close enough to land the hyper charge shots. Then Switch to the hammer use to the skies lightning field and try to knock the enemy back towards your turret with thundering blow.

Jayce is not meant to initiate with the hammer stance. What you want to do to help your team out is land a shock blast through an acceleration gate to weaken the enemies and then they can go in to deal damage while you wait for them and the switch to hammer stance and land "to the skies" "lightning field" and a "thundering blow"