I'll still stick by the Chen+Harpy Stormcaller as one of the most annoying openers in dota 2. It's about a 20% chance (if there's no harpies in the small camp, just do what Chen normally does). If there is a harpy, grab it, go to a lane, spam chain-lightning on the hero(es) 10 times. Any lane, but especially mid.
Bye-bye regen, bye-bye most/all of their life. Leave/lose the lane or die. Sure you'll share experience with a carry for a minute or so, but your opponent won't get squat. You'll feel like a god for all of two minutes, then you ditch the harpy on a neutral camp and do what you normally do (it doesn't last very long). It's almost like auto-winning a lane for a couple of minutes, sometimes even tri-lanes, often with first bloods coming your way. You'll remove a tango every 4 seconds from the enemy, then start harrassing them out of lane or killing them. Keep Chen safe though, they probably will dive the squishy SoB.
It doesn't seem like much, but that chain-lightning is a killer in the first couple of minutes. It's not the CC that other combos bring, it's not even assured (it's pretty unlikely actually), but if you see a harpy camp in your first jungle run-through, for god's sake grab it and win a lane for your team. It really is that good.