Countering Bloodseeker is a matter of winning the first few levels before he can get his Bottle. The typical Bloodseeker build is QB+Stout Shield+Healing Salve. Assuming you're a ranged hero, trade as much damage as you can as soon as possible. If he ignores you and goes for last hits, you can pound him harder than he regenerates. After you've done this twice, he's out of regen and too low on health to come to the creep wave. If you're a melee hero, you'll have a bit harder of a time because you'll take a lot of creep damage doing this, but the same concept applies.
If you let him get an early Bottle or Boots or a few extra levels and extra points in Blood Bath, winning the lane becomes significantly harder. Instead, you need to take whatever damage he and the creeps deal to you and harass him for all it's worth, as you can be safe in the knowledge that he has no surprise spells to pull on you (other than a 120 damage DoT which just allows you to hit him harder).
Abuse creep aggro constantly. When the Bloodseeker goes in for last hits, draw the creep aggro on purpose by right clicking him and then backing off. This will cause his creeps to harass you and your creeps to chase those creeps. You can then drop the aggro, step in front of the wave, and deal extra harass damage if he goes for the last hit, or simply mess with his timing and then deny the creep. If he tries to trade with you, just micro well and this is exactly what you want because you have adequate regen where he's relying on a single Salve to last him until his Bottle. As a melee hero, Bloodseeker needs to have a health buffer to go for last hits, because you can kite him as he tries to run out of range and hit him 4-5 times if necessary.
If you're a melee hero, it's a bit different. You have to be equally aggressive in trading harass but you also have to expend mana (if you're a melee hero without a nuke you probably shouldn't be mid in the first place) to force him off the wave. This is actually usually really easy.
Bloodseeker is a very weak hero: his only strength is his Silence which can be useful against heroes that rely on mobility spells. In order to counter him, all you have to do is carry a TP Scroll. If he uses his ultimate on you and there's no tower close by to retreat to, you just TP away. He can't stop you, and has wasted a lot of time and effort ganking that he can't afford to as a carry.
Alternatively, you can just dual lane mid and he automatically loses the lane badly, usually even if an ally comes to make it a 2v2. Specific heroes can also beat Bloodseeker 1v1 without any real effort in solo mid simply because they're much stronger heroes or have strong slows to force him off the creep wave:
- Venomancer
- Viper
- Ancient Apparition
- Tiny
- Sand King (Level E)
- Templar Assassin
- Luna
- Stormspirit
- Lich
- Warlock
- Night Stalker
- Batrider
I'd link to a couple of replays but I literally haven't seen a Bloodseeker in weeks because the hero is just terrible once people learn to always carry TP's.
EDIT: I finally came across a Bloodseeker!
Recipes are just the "extra piece" of an item that turn basic items into upgraded items. They don't do anything unless you have all of the other components already and should almost always be bought last. For example, a Magic Wand requires:
- Magic Stick
- 3 Iron Branches
- Magic Wand Recipe
If you have all of those, they combine into a Magic Wand. Not all upgraded items have recipes. Some items have multiple recipes, for example Necronomicon 1 with an additional recipe upgrades into Necronomicon 2, which upgrades into Necronomicon 3.
It's a very simple concept, just odd at first.
Best Answer
Don't die
No matter what: don't die! Your survival is more crucial than your farm; it is more important that you stay in lane soaking XP than it is earning gold. I assume you are mostly referring to being an off-lane (Radiant top lane, Dire bottom lane).
Last hit under tower
Ultimately, you want to keep away from the ranged heroes until you are more familiar with whoever who are playing and confident in your ability. It's best to stay close to your tower, and learn how much damage a tower does to each creep (6 hits for melee, 3 hits for ranged creeps) and learn exactly how to get last hits in between. Normally you'd want to hit each creep once (assuming your creeps aren't attacking it) and then wait for the tower to do 5 or 2 hits (depending whether the creep is melee or ranged) then get the last hit.
Keep creeps at your tower
Body block
You can block your own creeps (body block: stand and move in front of your creeps path to slow them down) to keep creeps near your tower
Aggro enemy creeps
As @Rishabh suggests, aggro the enemy creeps and let them follow you behind your own creeps.
Pull neutral camps
You can also pull the jungle creeps into the lane which will drag your creeps away. This is only advisable if the enemy has done the same, and your creeps are pushed up. This can also deny your enemy experience, and net you more CS (creep score) against those neutrals. Since your creeps will have less health or there will be fewer of them, the enemy creeps will make quicker work of them.
Which comes with its own risks
Be aware this comes with its own risks: your enemies may be able to push down the tower quicker which is not good news (whole team gets XP and gold, plus they gain map control). It's probably best to keep the enemies off your tower and forsake gold
Items
Buy sustainability. Don't worry about getting a Bracer or Null Talisman, focus on getting a Stout Shield, Tangos (buy 8 if you want!), health pots, Mangoes and Faerie Fires. It is far better to stay in lane than it is to have to leave. Leaving lane forces you to lose XP and gives your enemies uncontested farm
Kill neutral camps
It may be possible, if the enemy is pulling neutral camps into their lane and denying you the creeps, to kill the neutral camps instead. This will depend on who you are playing, but remember you don't want to lose too much health from doing this. It may be best to just stand within range of your creeps (XP range is 1300 as of 6.79 as @Joe points out in the comments)
Don't. Die.
Your death is very detrimental. Understand that it is far more important to go without gold from creeps than it is to give a death to your enemies. Doing so subsequently leads to other actions:
and an upgraded courier* which now benefits the rest of their team. They gain experience and can now start roaming to other lanes for successful ganksIf you are going to take too much damage for the sake of a last hit: leave it! It will be very frustrating laning against a duo who deny all creeps etc, but dying is far far worse! You want to stay away from dying, so play safe even if you lose last hits!
Practise!
Matchmaking sometimes takes 10 minutes to find a match. During this time, you could browse the internet, read guides or watch YouTube videos, or you could practise your last hits in the Demo Hero functionality (select Heroes, choose a Hero then select Demo Hero). Once your match is ready, it will alert you and you can select Accept to go into the match.
Note that as of the spring cleaning patch, a new training mode Last Hit Practice has been introduced for this exact purpose. This mode is better than the demo hero mode, as it focusses specifically on last hits (and denies).
* The courier upgrades to the flying courier automatically as of 7.07