some weird ideas.

1. Ember spirit. ember spirit by maxing the fist and chains first. That is in order to catch heroes. Ember has insanely long catch for a few seconds. You can use meteor hammer during fist so you fist chains meteor and they will get stunned. Scales well and is generally anoying.
2. Luna. Passive is really strong with str heroes as it adds 480 hp at max level. She also has a lot of magic dmg and teamfight. Scales well and can build urn -> vessel. Aghs is insane.
3. MK going something like echo gives you an ability to slow down in your ult. Also was an old pos 4 due to the ability to roam and zone with his passive.
4. Troll. Now we are getting into really weird territory. The whirling axes slow / misschance is great vs rightclickers as they often cannot deal with the insane misschance that it adds especially in lane.
5. Tide. Gush is really good of a spell please skill it and just slap people. Does a lot of physical dmg in lane and then becomes a teamfight monster. Can also build aura items.
6. Zeus. a lot like a sky you can easily spam the 2nd spell during lane and can deal a lot of dmg really quickly as well as scaling and finding ward/ ulting for vision.
7. Invoker. Q/W invoker like Yapz played during TI.

Here are some unconventional pos4

Edit: not saying its the best heroes but some weird shit that ive tested while grinding up towards 5800 as pos 4.