The only few heroes that have been often hyped about are techies and centaur, probably because techies is one of the more unconventional ones and centaur being predicted for the next release. Excluding the new heroes (which I have no idea what they do at all), I feel that it is time to reintroduce the forgotten old school heroes of dota.
Arguably one of the best carries in the game, you get an overpowered metamorphosis that gives you good range and good attack speed while being able to clone up to 2 of it. He can be considered somewhat of an anti carry with his first skill, creating a reflection of a targetted hero which slows and attacks him. His ultimate switches your current hp with the hp of a target, which is basically a slap in your opponent's face if you manage to pull it off. Back in the old days, people get dagon just to do the sunder-dagon combo, I'm expecting that to happen after the release of terrorblade since dagon got so much viable recently.
Used to be seen in competitive together with alchemist, like how we saw antimage vs morphling lineups during TI2. Fell out of favour after people realised anti-mage was a good counter to her. First skill is split shot which does the same thing as gyrocopter's flak cannons, except with reduced damage and no shot limit, somewhat of a range battlefury. Hoping to see that all split shots are able to carry orb effects so that we get to see some medusa when she's released, otherwise she's quite useless. Second skill is a nuke which travels through enemy units and deals damage while stealing mana of units that have a mana pool, otherwise known as medusa's ricing skill. Third skill is a shield that allows her to lose mana in place of her hp which explains why anti-mage counters her. Ultimate dramatically slows enemies who are facing her, and only recover slowly over a period of 5 second. One of the more useless old school heroes in my opinion.
Probably attacks the fastest within the game on an overall basis, used to be pubstomp carry of choice. His first skill allows him to switch melee/range whenever which allows you to dodge projectiles if you time it correctly, the melee form gives a bash. Has some sort of a nuke which whirls around him while in melee and point targets while in range. 3rd skill is a passive which allows him to attack faster with each consecutive attack and his ultimate is a global buff which gives allies and yourself faster attack speed.
Has not been in slight relevance to the metagame for around 3 years. First skill is a goo which you have to continuously stack on your enemy. Napalm is indefinitely superior to goo as its easier to land (harder to juke), and the slow effects are better. Bristleback's second skill is quill spray which similar to goo, you have to continuously stack on a unit to see its cumulative benefit, otherwise, the damage is quite insignificant. 3rd skill is a passive which gives him reduced taken damage if damage is taken from his back (Rubick has magic resistance in an AOE without having such shenanigans). Ultimate is a buff increasing damage and movement speed if you maintain your combo of goo and sprays.
Lord of Avernus
Appeared for quite a bit during Happyfeet/Mineski's reign, was the last time I saw him in competitive. Quite versatile as a hero, you can play him as support/tank/utility/carry. First skill is a nuke/heal depending on who you use it on. Second skill is a shield which you can play on allied units, explodes and deals damage to enemies if damage exceeds limit. Third skill is a passive which slows the enemy you are attacking and any allies attacking the unit under the effect of your passive gains an attack/movement speed buff. Ultimate allows him to absorb damage taken for a period of time, automatically activates if health falls below a certain level. Good for diverting focus fire, don't see the point though.