Shyvana's abilities have no cost related to them, and the use of her abilities is only limited by cooldowns. Instead she uses Fury as her secondary resource.
Fury is only needed as a requirement for the use of her ultimate Dragon's Descent, which allows her to change form if she has Fury and remain in that state for as long as she has some left. Shyvana won't generate Fury unless she has at least one point in Dragon's Descent, and once she puts the first point on the skill she gains 100 Fury immediately. Any gained Fury cannot be lost except by depletion during Dragon Form.
Shyvana gains 5 / 10 / 15 / 20bonus armor and magic resistance, doubled to 20 / 30 / 40 while she is in Dragon Form.
Twin Bites flat cooldown reduction is not effective against structures.
The only exception to Dragon FormTwin Bite applying on-hit effects to all affected targets is Tiamat and Ravenous Hydra's passive effect Cleave, as it has an internal cooldown of 0.05 seconds when triggered on different targets. This is a special case to prevent abuse.
Active:Shyvana surrounds herself in flame for 3 seconds, dealing magic damage to nearby enemies each second, increased by 20% against monsters, and gaining bonus movement speed which decays by 15% of its original value each second.
「 Magic Damage Per Second: 20 / 35 / 50 / 65 / 80 (+ 20% bonus AD) 」「 Magic Damage Per Second Against Monsters: 24 / 42 / 60 / 78 / 96 (+ 24% bonus AD) 」
Dragon's Descent has an effective duration of 20 seconds when not attacking. When permanently attacking at 2.5 attack speed, it has an indefinite effective duration.
Dragon's Descent has an effective cooldown of 150 / 75 / 50 seconds when not attacking. When permanently attacking at 2.5 attack speed, it has an effective cooldown of about 17.65 / 15.8 / 14.3 seconds. With Sated Devourer, the effective cooldown is reduced to 12.24 / 11.32 / 10.5 seconds.