This build works best on 5v5 with a team member jungling.

Pro's
-Extremely strong ult
-easily heal fast with consume
-get away fast
-2 ways to slow enemies
-slow deals tons of AP damage
-speed up allies and yourself
-Quite durable

Con's
you will take a lot of damage while using ult
if you don't have your ult you can get ganked if not careful
slightly squishy in beginning so be careful to start.

If you are playing 5v5 then try to get someone on your team to jungle and cover top or bottom by yourself gaining experience from minions killing eachother. Don't get too cocky and push. Let them push you back to your turret and consume to preserve your life as long as possible. Harass them with ice blast when you can to keep them at bay.

If youre playing a 3v3 then again try to get someone to jungle and help cover both lanes.

Once you get to the point that you have about 2k gold have the jungler cover your lane till so you can go buy another item.

When youre in a team battle try to come up either even with them or just behind, and slow 2 people and attract attention. Once a couple people start attacking you, use your ult and make sure that your team is right there to slow and kill the rest once your ult is done.
NOTE: dont waste your ult if only one player attacks you, also make sure you are the first one to attack during team battles so that you can do maximum damage with your ult. Make sure you have some sort of AP item before trying to gank.