"After taking the blue rose you'll be sent to the unknown world again and this time you'll gain a new ability which is Angel Boost.
To use Angel Boost you'll have to jump and press Q+Space in the air.
Make your way across the gaps by using Angel Boost. The level was made so you'll be able to practice using it. Although this ability isn't useful at all in battle.
In addition to getting a distance boost in your jumps, you can also continue pressing Q in order to reach further. Although this is only helpful if the platform you're trying to reach is lower than the one you came from.
You can also chain Angel lift with Angel boost. First use Angel lift then press Q+space to boost you forward so you can reach the next blue crystal and use your Angel lift.
On the last platform you'll have to use Angel boost quickly followed by Demon pull to pull the floor near you and Dante will automatically land on it.
Now make your way to the stone figure and destroy it with Arbiter in order to get back to the real world.