Unlike League of Legends, Dota 2 does not have a dedicated jungler role.
The odd 'soft support' in its stead is probably the most difficult Dota 2 role to play. The hard support's task is to enable their carry and not all that much else The soft support, on the other hand, technically bears the duty of enabling the whole team.
They create momentum in an otherwise tame matchup and exploit whatever kill opportunity the game offers. This also tends to involve moving around the map a lot, which is why the soft support in Dota 2 is also referred to as a 'roamer'.
The following 5 heroes are arguably the best Dota 2 picks that fit this bill
5) Bounty Hunter
Bounty Hunter is one of the few Dota 2 heroes whose names spells out exactly what they are good at. Many roamers have one or two core spells that enable their roaming potential. Bounty Hunter, meanwhile, has his whole skillset dedicated to sneaky rotations.
His Shadow Walk lets him zero in on the target undetected. His Jinada gives him physical burst damage to potentially insta-gib squishy intelligence-based cores. He has one of the strongest lvl 1 nukes in Dota 2 with Shuriken Toss. His most iconic spell, however, is Track, which trails a target through invisibility and gives him extra kill bounty.
All other Dota 2 heroes on this list excel at pick-offs. Like all of them, Mirana has the bread-and-butter roaming kit: a nuke to clear waves and push dead lanes, a long-range skillshot stun, and a mobility spell with stacking charges both for engagement and disengagement. But Mirana particularly excels at co-ordinating bigger teamfights with her ult, which cloaks all her allies in global invisibility.
3) Spirit Breaker
What is the point of a rotation in Dota 2? In short, it is to tip the scale of balance by overwhelming a lane with numbers and throwing out the odd disable to seal the deal. In general, this is the purpose of a roamer's life.
By this logic, if there is one Dota 2 hero who exemplifies the roamer slot, it is Spirit Breaker. Charge of Darkness is a global engage spell which also gives vision over its target as Spirit Breaker hones in at break-neck speed. Picking Spirit Breaker means endless diving and clashing, as the allied midlaner always keeps him on speed-dial.
Pudge is the highest picked Dota 2 hero of all time. This is hardly a surprise for any Dota 2 player, as they are used to seeing a Pudge at least once every three matches or thereabouts. Oddly enough, the one time Pudge presents very little threat is when he shows up in a lane. But a missing Pudge is the very aspect of terror - every player on the map aware of this, restrict their movement to a great degree.
If they do not, they get caught in a Meat Hook from the fog of war, dragged into their eventual death. This makes Pudge one of the few Dota 2 heroes who is rewarded for constantly staying on the move, growing in Flesh Heap stacks with each kill.
1) Earth Spirit
Topias 'Topson' Taavitseinen, OG's midlaner, is famous for his midlane Earth Spirit. Granted, the midlane Earth Spirit in DPC is otherwise unheard of. The reason Topson gets away with it in the mid lane is also the same element that makes Earth Spirit such a good roamer - mobility.
Earth Spirit's credentials as a ganker are off the charts, so much so that entire laundry lists of nerfs throughout several patches haven't been able to stop him. He is arguably the most difficult Dota 2 hero on this list. In return, he offers utility in spades: a silence, a stun, a slow, and a huge initiation range, coupled with a damage-over-time ultimate.