The cooldown on that is WAY too short. Remember that 30s is more or less the amount of time between waves. Even at 2.5s channel that would be super easy to just get away from ALL ganks at any time with this. Even if you deactivate it after taking damage like how Majestic Leap works, it would just become mandatory in order to contest Bridge buffs and Urn. Even at T3 it would be under priced.
If the Cooldown was something more like 200s you might be able to justify it.