Doom is pretty versatile. He's one of the few heroes that can literally go anywhere. Jungle, offlane, mid, safelane are all options.
Jungle doom is unfortunately weak currently. Very rarely will you see a jungle doom in competitive play, and when you do it's almost
always going to be an early fight/utility Doom who gets mek and mana/phase boots and perhaps grab a vlads/drums/vanguard/blink.
The reason it's weak is because of the recent changes to the jungle and nerfs to certain key items. First, easy camp and medium
camp got switched, so you take more damage doing your normal jungle routine and will most likely have to ferry a salve to yourself.
Second, the cost of Midas was increased which slows down his progression even more. Third, Shadow Blade used to be a core pick
up on him, but the cooldown was nerfed from 18 to 28 seconds, and one of the selling points to jungling him is that you never know if
he's missing or not. The biggest problem with Doom in the jungle is that you're relying on your team to play 4v5 for the first 10
minutes so you can farm an item. This is why Mek is a common choice for jungle Doom, because Mek is usually the most effective
item to come out of the jungle with at ~10 mins and will make up for your absence. From there you push tier 1 towers down. Blink
dagger is a good choice as well if you already have a healer and tower cheese(insert Terrorblade).
If you're going to jungle doom, start with Stout shield, tangos, and Quelling Blade. Know how to use choke points(
) tojungle. Know what every neutral creep(must read) can give you. Look for wolves. Dire jungle is more advantageous for Doom
because the medium camps are right next to each other and can both be seen as they spawn at 0:30 from the hill in between them.
If you don't get wolves, go to the big camp and clear it with devour. If centaurs spawn in the medium camp instead of wolves, you
have to use devour on the centaur. The key is to clear as many medium camps as you can to try and get Wolfpack Aura. If you're
lucky enough to get it in the first couple mins, Wolfpack Aura gives you a ~6 min level 6 as opposed to ~7 1/2 min. Ferry a
Basi Ring to yourself as soon as you have the gold, but make sure to check your mid player's gold so that you don't steal the
courier. If you have to wait for him to deliver his bottle to himself before you get your Basi, that's fine, don't delay your mid hero's
items. Some people like Bottle instead of Basi. Test it for yourself. Either way, you need some kind of mana regen so you can
spam your scorched earth. I like Basilius because it gives 3 armor, 6 dmg and 0.65 mana regen.
Offlane is something I've seen even more often than jungle Doom recently. Start with brown boots because he has 290 move
speed, and tangos with a pooled ward. Perhaps a pooled tango or two if you have more than 1 support. Doom has good starting
strength and a 3.2 STR gain per level which makes him viable for the offlane in SOME situations. He however has NO ARMOR
at the start which means you have to play chill until you can grab a Basi Ring or something else. Devour allows him to still gain
some gold despite being zoned from lane. His Scorched Earth allows him to gain 16% move speed and regen some HP while
they're trying to kill him. If the supports are pulling/missing it can be used aggressively to shove their carry out of lane or contest
the pull to get yourself some farm/xp. Scorched Earth does 120/216/336/480 damage/heals and every use of the ability has to be
used well. How you skill your abilities in the offlane is always a case by case basis and depends on how aggressive you can be
versus them. Place your ward in their jungle at the start so you know whether it's safe to roam and devour a neutral. Courier
either Basi/Bottle/Bracer or perhaps a Poor Man's Shield(not sure about this one) ASAP but don't steal courier from mid.
Lane Doom is my favorite way to play him. You're able to get max devour which gives you an insane amount of net worth.
Start with Basi+tangos or either tango+salve+ring of protection if you need more regen. Basi is needed for a few reasons.
The mana regen allows you to spam devour whenever it's off CD, it allows you to use lvl 2 scorched earth and regen yourself
when you get harassed(remember, you only started with 4 tangos), and it allows your supports to use their spells more often
to zone the offlaner. Also, when it comes time to push tower, the Basi aura will give your creeps armor which is essential.
You should direct your supports to scout the jungle and see which neutrals have spawned. If nothing good spawns, they
should stack a medium or big camp to hopefully get something good. You will want either Satyr's Unholy Aura(4HP regen
per second), Wildwing Ripper's Toughness Aura(+3 armor), Centaur's Swiftness Aura(+15 attack speed), Troll skeletons,
or Wolfpack Aura(+30% dmg aura w/ 20% 2x crit). All of the auras are nice, but Wolfpack Aura is your bread and butter.
Winning the game becomes a whole lot easier. Build Phase Boots or Power Treads. After that you have many options and
I suggest you experiment and decide what you like the most.
I like rushing Necronomicon and here's why: Despite the armor nerf that the Necro book summons received recently,
Doom makes it less relevant by being an insanely fast farmer and obtaining the 2700 gold needed quite quickly. He is also
going to be carrying an aura that will help out the Necro Minions. The stats you get from Necro are perfect for Doom as
well. +8/12/16 Strength and +15/21/24 Intelligence. This gives Doom the mana pool he deserves and more Strength stats
to increase HP buffer. Once book 1 is completed(~10 mins) you can easily take the Tier 1 Tower. If you get the tower last
hit then you will be well on your way to book 2. With book 2 completed(~12:30 mins), you can march down lane and push
the Tier 2 Tower. Not many lineups are able to handle a Doom with book 2 and either an armor/attackspeed/damage aura
pressuring their Tier 2 that early into the game. Another thing to note is that Scorched Earth also affects units under Doom's
control. This allows you to heal your summons while pushing the tower if they take damage from spells or tower aggro.
Next item after Necro 3 is typically BKB but you could also purchase either Blink, SnY, Shadow Blade, or turn your Basilius
into a Vlads and take Roshan. Late game items include a combination of Assault Cuirass, Heart, Abyssal Blade, Shiva's, Desolator,
or even Mjollnir(for the shield). Assault Cuirass is typically your best bet since you want to get as many auras for your team
as you can. The armor is great for your Necro summons and AC works against enemy towers, so breaking base is that
much easier.
With this build you would have Wolfpack Aura(+30% dmg & crits), Vlads Aura(melee lifesteal, +15% dmg, +5 armor,
0.8 mana rgn), Necro Archer aura(+9% AS/MS), and Assault Cuirass(+20 AS, +5 armor, -5 armor to enemies) giving a
summation of +45% damage, +10 armor, +9% Attack/Move Speed, +20 Attack Speed TO YOUR WHOLE TEAM,
CREEPS, AND SUMMONS.