Aghanim’s Labyrinth – Wyvern Boss (Apex Mage Difficulty)

Hey reddit – I've been struggling a lot with this boss today. The two challenges I have are as follows:

1. Frost orb/breath (looks like puck's illusory orb that bursts at the end of its flight. The boss periodically throws this out while landed) – With moderate movement speed (skeleton walk and tranquil boots active) this ability still slows enough that if I am targeted again, I am almost always hit, and 2-3 hits are fatal.
2. Green ice spikes (unlocked at a certain health threshold. Boss settles in the center and channels. You are ground targeted with a slowing ice circle that bursts for more damage if you stay in it the full duration) – This ability seems to auto-target players and instantly slow them. The ticking damage is severe, and the slow is strong enough you are stuck inside for 2-3 ticks. The burst is usually fatal. I've never survived this without some kind of immunity or crazy healing. Though the first group seems to miss players entirely, there are 3-4 casts of this ability during the channel.

Does anyone have any advice about this boss? Thank you!