Do I need a friend?
- Bloodseeker's strength is the mid-game. Carries can be either item-dependent, experience-dependent, or both. BS is both; he needs to accelerate to level 6 (akin to skeleton king) and he needs items to supplement the initial damage burst from his ult. This is the reasoning behind why this hero is played in a solo lane.
- If you aren't playing mid you've already hurt your team composition. The probability of you getting enough farm solo in an offlane situation is minimal. If you do get enough farm to gank because you're against bad players, there is only one logical lane to gank, limiting your options and making your movements predictable. To keep your options open, and to not stack the odds against yourself, you play this hero mid and you should be looking to see what the opposite team will play against you.
Bloodseeker's strength is that his kit gives him everything he needs to lane well. Supports essentially do the same thing, that is, ensure the ability of the carry to farm. This means in a one v. one situation they aren't necessary.
"What if you're against a duel lane?" The best answer is to switch lanes to the solo one. You don't offer anything to a duel or tri-lane until level 6 so odds are that you will be outlaned. Always be thinking early game about how to maximize your experience and gold gains to get to level 6.
You've either randomed or picked this hero and you are eagerly awaiting what your lane matchup will be. Whoever it is, keep in mind the following ideas about the strengths of your hero:
You have high sustain, if it comes down to a war of harass you will win every time because of your health gain upon last hit. This suits you well for low damage burst (DPS or otherwise) heroes.
You're a lane bully. You have the immovable rock thing going on; you gain health on last hitting, it is nigh impossible to out last-hit you, and the amount of denies in the lane phase ensures you will hit 6 first.
You deal physical damage, the solo-mid role is well suited to you because strength gain and armor on int heroes is (usually) low.
Until ultimate, upon which you will start moving between lanes, you have only one cast-able spell.
Everything just presented relies on the fact that you can last hit like a professional. If you cannot last hit then you cannot play this hero to maximum potential. There are zero builds that will recommend you not get Blood Bath first, it is because of this assumption.
So look at the other mid, first and foremost, can you out last hit them? If it's exort Invoker then that will be how the lane is decided. Are you laning against Silencer? You do not have an early spammable skill and your ability to last hit under duress will decide the lane.
The order I go through sizing up my lane looks like this:
What is the difference in last hitting power?
Is mana important?
Am I facing a hero meant to absorb harass?
What is the defining feature of the hero? (Tinker:high burst, OD:int steal, DK:tanky)
I will not detail the skills in this section, for a complete understanding check out the Dota 2 wiki page. Rather, I will summarize them and put into perspective how they fit into your ability to dominate lane and gank.