Pusher

A pusher hero stays in the back of the battle more often than not. They aren’t the ones who jumps into battle to fight, but rather stays behind and cast creep producing skills to assist the team during raxes. Summoners are usually classified as "pusher" heroes, with their plethora of minions.

One of the best pusher heroes is theProphet. His treants can be cast on anywhere with trees to summon 5 treants at max level, which results in a very fast push rate. This can be incredibly useful during pushes, if he casts the ultimate skill on a bunch of mass creeps, the hero who gets hit later on or at the other side of the map would receive a whooping high damage.

Pushers are able to quickly push towers down by sheer amount of summoned units or being able to quickly take down incoming enemy creeps. The Undying is a good pushing hero, as he can summon zombies to tank enemy creeps and quickly take down the enemy tower. The Warlock has an Infernal as his ultimate (two -- with Refresher Orb) which is also a great ability to push lanes. The Shadow Shaman also is a good pusher with his ultimate (22 wards with Refresher Orb and Aghanim's Scepter).

In Summary
Not a good head to head fighter and is very dependent on skills to force his enemy to give up and retreat. Easily killed if not careful and is able to help ally heroes by pushing towers quickly.