Best Push Heroes for Roles 4,5?

 

Chen and Enchantress are the two strongest push based heroes. However, they require a great deal of micro to be effective and against a team that goes midas heavy or has decent anti-push, they fall off fairly hard if towers are not going down by the 10-14 min mark. Outside of these two micro-intensive heroes I would suggest:

1. Venomancer - Venomancer can operate on an incredibly low amount of farm if need be. However, once Plague Wards hit L4 he can actually farm both lanes and jungle fairly efficiently in order to catch back up.
   
2. Leshrac - A nicely scaling stun, a composite damage AoE that eats up towers ( Diabolic Edict). With the change to Lightning Storm he can farm waves fairly easily as well.
   
3. Jakiro -  Liquid Fire is an incredibly strong pushing tool now, especially with no mana cost. It can push both waves and towers fairly well, though he rates a bit lower due to the fact his auto-attack is so abysmal and his  Dual Breath no longer wipes out creep waves as quickly.
   
4. Enigma  - If you can time the Eidolons correctly, especially through the conversion of an enemy creep he can push down towers fairly efficiently.
   

One of the most important things to note is that team synergy means a lot more in terms of how efficient and able you will be to push. Picking heroes that compliment your team and provide the pushing power is almost more important than trying to pick the individually strongest 'pushing' hero.
Examples:

1. Your team mate picks Lycanthrope. An early level of Howl suddenly makes support heroes with minions far more effective at pushing, raising the value of support like Enigma  for early push.
   
2. The enemy team picks Treant Protector. Heroes like Jakiro and Venomancer become more valuable in their ability to knock off the  Living Armor ticks quickly so that the tower continues to take damage, while a hero like Leshrac loses pushing efficiency as the  Living Armor eats pulses from his  Diabolic Edict).
   
3. Your team selects, Necrophos (core), Dragon Knight (mid), Centaur Warrunner (off), Rubick (4 + teamfight) and Omniknight (5). Alone Omniknight does not look that efficient at pushing. However, having this team hit fast level 6's it suddenly becomes a nearly unstoppable deathball to towers due to multiple sources of healing (fast Mekansm on Necrophos ), tons of AoE, great ability to zone out (Centaur + Dragon Knight), and Omniknight early levels of Repel to make Dragon Knight magic immune while eating up towers.
   

It is about finding the support that is going to actually provide the best synergy to your team or the strategy your team is trying to execute in the end.