Question regarding Jayce

UUh, you can only use 1 at a time unless regarding both of their base passives. The runaans is only when he is ranged and the hydra is when he is melee. But the base stats stay,

Basically, when you're in your cannon form, your Runaan's shoots the two bolts but no Hydra passive and in hammer form your Hydra activates and your Runaan's orb thingy disappears. The base stats (70 perent attack speed, 12 percent lifesteal, etc.) would stay in both forms.