No, this isn't related to balance, and is actually strategy related.
The origins of banning heroes comes from a match type called -CM, or Captain's Mode in DoTA. In Captain's mode, teams take turns banning heroes they don't want the other team to use whilst picking their own heroes for the match. One person from each team (the person in the first slot) is the one who makes these decisions, so you usually only play CM with a group of people you're familiar with since it requires a lot of coordination.
In professional level play, this becomes extremely important as you want to prevent the other team from picking heroes that they are adept at, or countering the heroes you picked.
For example, say you wanted to go with an "all push" strategy that relies on pushing down lanes to end the game fast (with the drawback that if you don't end the game early, the other team will easily overpower you over time with their "late game" heroes). Your team will probably want to ban any heroes that can counter these pushes, or easily kill their heroes.
While balance/imbalance can certainly have a factor from patch to patch, professional level play sticks to a version of the game that is considered "stable" by the community.
To begin with, early game Slark is essentially about as menacing as a paper napkin. Slark needs a pretty decent baby sitter to survive early game without heavy harassment. After Slark gets to level 6 things get trickier, but the fact remains that Slark has no survivability when faced with nukes.
So the effective counter heroes will deal heavy amounts of burst damage and essentially kill Slark before he has time to fully finish his combination of death pact, shadow dance, and leech enough stat points through essence shift.
While you may not always be able to team up to kill a hero, it is still recommended to try to wrangle at least 1 other teammate to assist. But given your criteria, and whether with support or without you will need to provide truesight. So wards, or dust if you intend on going 1 on 1.
Heroes
Lina - unloading the early/mid game combination of her light strike array, dragon slave, and laguna blade
Bane Elemental - brain sap, fiend's grip, follow up with another brain sap - items to get in the mean time, necronomicon so that the minions can pound away while you disable
Leshrac - between diabolic edict and pulse nova Slark will have a pretty hard time standing directly next to you or even using pounce. On the off chance you are pounced on split earth should be like shooting fish in a barrel to land. And you still have lightning storm to cast.
Nerubian Assassin - mana burn, impale, vendetta, attack, repeat whichever skill is done it's cooldown.
Items
- observer wards
- sentry wards
- gem of true sight (situational)
- necronomicon - (upgrade this) minions for added dps and on-demand true sight
- blademail - synergy counter as
essence shift and damage incoming is redirected
- ghost scepter - disable Slark
- eul's scepter - disable Slark
- force staff - to break pounce link
- blink dagger - to break pounce link
Best Answer
The official page doesn't specifically tell us anything, except that the damage from cleave is reduced by armor, and not by magic resistence.
Thus, we can conclude that the damage done is physical, thereby not affecting units in the Ghost form.
If somehow they do damage them, it's just a bug and should be fixed in the upcoming patches.
EDIT: Confirmed. P.S.