This guide is the build I have mainly been using and I have had quite a lot of success and fun with it. It is designed around being a roaming support/utility hero that can help tip the balance in 1v1s in lane and even 1v2s sometimes. It takes advantage of Medivh's unique trait Raven Form which makes him arguabley the best roamer in the game. This build also allows for you to still be effective in the middle of teamfights during the late game as Ley Line Seal can help you engage, escape or disable enemies mid-fight. This works best when you can communicate with your team but I have mainly been playing solo and have had good success with it still. I hope you guys like it and if you do please upvote :D

Medivh is extremely strong but also very hard to play and I by no means consider myself the best but I do think I understand what I should be doing with him.

PROS
+Useful in many situations
+

This build is mainly focused around Medivh's trait, Raven Form . Raven form allows you to fly around the battlefield invulnerable and over terrain. In the early game you want to assist whoever you can by flying lane to lane looking for opportunities to kill an enemy or just put pressure on them to help your teammate. Your first talent is Raven's Intellect give you double manna regen whilst in Raven Form and lets you spam spells and travel the map without needing to return to base. After this you get Bird's Eye View which help you scout for your team and scan the area for enemies more effectively; you can swap this out for Dust of Appearance if the enemy team has a stealth hero. Winds of Celerity is picked up at level 13 so you can roam faster, just works well for this build in general.

This build is made Medivh to be a utility hero so don't go super aggressive with Arcane Rift ! It is useful in order to chip away at enemy heroes and help clear lanes a little bit but this does not mean you should chase down your enemies with it as it is unlikely they will actually die to it. I chose Arcane Charge over The Master's Touch as I think it is more consistent and The Master's Touch encourages you to be much for aggressive which is not what this build is about.

Force of Will has enormous potential but should not be held onto too much in order to get that amazing clutch save from Tracer's bomb but at the same time not wasted for nothing. It can take some time to get used to but use it if you are about to teleport and are being chased or when an ally is engaging the enemy. It is sometimes good to hold onto it though if you know the enemy has some nasty burst they could be waiting to use. Enduring Will is the talent this build uses as more protected time means more time you or your team can fight for. If you have no healer then Reabsorption is a good pickup, not the best healing but some is better than none.

Medivh's ultimate is depends on the situation you are in. I usually ended up Ley Line Seal as I found myself picking it more and think it has a huge power in many situations. It can be used to initiate and set up your team to combo the enemies quickly; useful for escapes as it is quite a long stasis and will allow you to mount up and run before they can chase; it is also useful mid-fight in order to disable a DPS hero or support in order to get a crucial pick-off. Poly bomb is still quite strong and I have had some massive chains of it especially when you get the level 20 talent for it. I would always pick it when up against The Lost Vikings as not many people can spread with them well and even if they do it still delays them in the middle of a fight or chase. Poly Bomb is also very good if they enemy are very mobile and hard to hit with Ley Line Seal (eg. Illidan, Tracer, ect.).