Interesting idea.

I have no problem with Snipe as is, other than the co-ordinated attacks. Co-ordinated Snipe attacks are something I would imagine won't last long in the balancing process; a couple of ways to get rid of it are:

A ) Snipe does less damage if it hits in quick succession (so the more snipes you take, the less damage each one does),

B ) Tracking Device only affects the player that puts it on you. So the rest of the enemy team can't see you to snipe at you just because one of them can. I don't see a massive problem with this as that person can relay your position to their team mates.

While we're on the subject of snipe, I'd like to see it buffed in one way; in the current build the damage it deals is affected by armour (more armour means less damage). I'd like to see either no armour mitigation from snipe or the opposite, so more armour means more damage. I argue this because common sense dictates that when you snipe a target you aim for a weak point, and because Snipe no longer does the damage its tooltip says because of enemy armour (although I recognise this works against my argument for more armour = more snipe damage).

Take that, Rook.

Nice Idea, you can pretty much relate your idea exactly to Mirana's Arrow from Dota, except it moving at a faster speed and greater distance... which would be incredibly fun to use.

Nice idea, i agree with Evanescent.

I thought this (about the armour vs skills) as wel. Then I noticed my Snipe was getting odd numbers well below what the tooltip was stating.

Bug? Or just me being unobservant?

I undoubtly stole this from dota but why change a good thing.  I mean that is what makes mirana of of the most fun heroes to play.  I don't know would be nice to see more aimed spells so there is more of an accuracy element and not just always point and click which gets dull sometimes.