Without a doubt, Soulstealer is one of those Heroes where skill (or the lack thereof) really shines through. The difference between somebody who knows what they are doing with Soulstealer and somebody who does not is clearly visible in games, and it's no surprise that in the hands of a skilled player can single handedly win games. A lot of people attribute Soulstealer's difficulty to landing Demon Hands, one of the most fickle abilities in the game. This is only half true, however, as there's a lot more to Soulstealer than meets the immediate eye. In addition to landing his Demon Hands and Soul Bursts, Soulstealer is a Hero who is naturally at a disadvantage towards all other Heroes in terms of HP. To make up for this, Soulstealer has the gift of being able to clear entire creepwaves in less than a second, allowing him to make items quickly. A blessing but also a curse, his above average farming skill must be utilized to it's fullest potential to be truly terrifying.
No surprise here, Ophelia is probably one of the most microintensive Heroes in Heroes of Newerth. With the recent addition to Energizer, an item that provides not only her but also her minions with increased speed and unitwalking, it remains to be seen how her ganking potential may be boosted if the item proves viable. Overall, Ophelia has been viewed as an arguably underpowered Hero, able to control only one Minion up until level 5, a severe nerf to the arguably overpowered version of Ophelia that preceded the current version. Nevertheless, some players hold fast that Ophelia's reward is worth the risk, believing that with the proper micromanagement she could be worth her weight in gold.
Flux is a Hero that isn't naturally difficult to play in the traditional sense. His abilities are quite straightforward, even with the push/pull polarity swaping, it isn't that complicated. Even his Q ability, arguably one of the more tricky things to master in terms of split second decision making, can be mastered by a decent player after only a few tries. No, what really sets a good Flux player apart from a bad one is teamwork and communication, one of the hardest things to come by in Heroes of Newerth. Flux is probably the most worthless Hero in Heroes of Newerth if not combined correctly. Even with a proper team, however, Flux is still a risky business. His ultimate, although on a relatively short cooldown, can actually do more harm than good when misused and unlike other initiator Heroes like Magmus, offers no real reliable stun or damage output. It's not surprising, then, that we don't see Flux in many games. The ones you do see him in and used correctly, however, are some of the most entertaining things you will ever see in your Newerth career.
Legionnaire is the forgotten Hero of DotA days. A pub favorite for some reason, Legionnaire seems to make appearances in all the wrong places. Although you might not see the connection at first, Legionnaire actually has a lot in common with Soulstealer. Both are at a massive natural disadvantage, a gap that they must bridge using their above natural farming ability. Legionnaire is one of, if not the best, neutral farming Hero in the game. This is largely due to his ability to deal more damage depending on how many creeps are attacking him, all for no Mana cost. The problem with Legionnaire is his schedule- should Legionnaire spend his time farming, or ganking? Both! But to which degree? Many players feel the need to rush a Portal Key à la Tempest, a strategy that often falls on it's head because Legionnaire often needs a Helm of the Black Legion, boots and a Chalice or other Mana source first, a long list to check before he can move on to his trusty Portal Key. A good Legionnaire player knows what he's doing, and is never wasting time. When he's not farming, he's ganking, and when he's not ganking, he's farming. He knows where he needs to be all the time and is always right on time.
The initial release and now the full release of Monkey King had a lot of people complaining. The consensus seems to be "why should I play this Hero when I can play a more reliable melee ganker?"- a question that isn't very easy to answer. DotA and HoN's Metagame has always been about reliability. Reliable stuns, reliable carry, reliable ganker. This is why Heroes like Magmus, Andromeda and Witch Slayer will always be top picks, because there's no chance of failure. Monkey King is the opposite of everything you'd want from a competitive Hero; he's risky and he's difficult. That said, Monkey King might just be one of the most powerful Heroes in the game, and I don't think we've even begun to see his true potential. Monkey King's strongest ability often goes unnoticed by players- his ultimate. No, not the movespeed buff- the cooldown reduction. Every time Monkey King casts a spell, his cooldowns are reduced significantly. Put this on a Hero with 3 activated damage abilities with low cooldowns, and you have a Hero that is capable of almost 0 downtime- Monkey King can effectively spread his abilities out in such a manner that he's almost always casting something, which puts him at a considerable advantage over other carry Heroes. Carry Heroes in HoN are characterized by the fact that most of the time, they would rather be standing still and auto attacking to maximize their damage. Monkey King on the other Hand, maximizes his damage by flying all over the place and completely disorienting his enemy. The difference between Monkey King and other Heroes is that he has to plan out what combination of abilities he's going to use in what order to match the situation he's in, a task not easily accomplished. When will we see Monkey King in higher level play? We can only hope soon.