Start with tangos and salves with 2 ironwood branches to combine into wand later on. Depending on the match up, almost always get stout to minimize the harass taken from the enemy team, or/and get a quelling blade to offset Pangolier's low base damage.
Deliver salves, tangos, and clarity potions if needed. Buy boots next to move around the lane and jungle quicker to get xp.
If you are struggling with harass in the lane, don't be afraid to eat tangos off of your ironwood branch for double the regen.
If the enemy team has a lot of spells
Get a magic wand and infused raindrops.
If the enemy team has a lot of physical damage
Get a ring of aquila.
If you have a hard time against laning, don't forget to buy the tome of experience. Level 6 is your power spike.
Power threads is great for Pangolier because of the extra strength it provides, synergizing with his 'Shield Crash' ability to reduce the damage taken. It also provides a bit more mana if you thread switch to int when pushing the lanes with the Q+W combo.
After farming lanes and the jungle with the Q+W combo, get a diffusal blade as soon as possible. Diffusal blade will allow Pangolier extra damage and mana drain
off of his Swashbuckle, as well as to cast a purge on enemy heroes for chasing.
If you are having trouble farming, I would suggest that you buy a javelin for the extra 25% proc for 100 damage on your Q ability and then later on, turn it into MKB if needed.
For team fight purposes, I would suggest on going blink dagger
next, to initiate with rolling thunder as well as to chase any fleeing enemies. Blink dagger provides the needed mobility to help Pangolier position himself in team fights, as well as to chase enemies and focus supports down because of his innate durability which is his Shield Crash.
By buying blink dagger, you can also chain stun a hero for 3 seconds if you initiate with Rolling Thunder and blink back to hit them again with Rolling Thunder.
For the last core item, a Linken's Sphere
is needed to evade stuns and single target disables when initiating. It also provides the needed stats for Pangolier as well as hp and mana regen for sustain in team fights. As a utility hero, you can also place the Linken's buff on your allies if they are always focused by the enemy team.
Pangolier's items can adjust depending on the team composition and the enemy lineup. All of these items
For team fights and more crowd control:
A shiva's guard
is a must-buy item. The active ability it provides synergizes with his ultimate ability and blink dagger, hitting almost every enemy when initiating. It also provides a lot of armor, an attack speed slow aura, and the needed mana for spamming his Q late game.
For focusing important heroes:
To focus down an important enemy core in a team fight. Abyssal blade
provides a bash for your Q ability, as well as the active stun to focus down heroes with bkb
If the abyssal blade is not enough, you can always get a scythe of vyse
to take care of the important cores in a team fight. Your primary job is to disable as much heroes as possible in a team fight so that your team can damage them without any counter play.
If they ought to have a linken's sphere, you should always have your diffusal blade proc the spell block, and then use the abyssal blade or the ginsoo's scythe of vyse.
All items in this category are purely situational. I would normally advise to follow the normal guide, but I would also suggest to adapt to the flow of the game.
If your team lacks damage/does not have a carry:
Getting an mjolnir
helps Pangolier's damage output and provides a decent amount of attack speed. The chain lightning also procs on his Q, so this item is great for him. The active ability also synergizes with him because he is always in the center of a team fight.
Against a magic damage team composition:
You would not probably get BKB
because of Pangolier's innate durability. But if the enemy team is focusing on you in team fights, a bkb will help you gain the immunity from magic damage and disables.
also helps in silencing and focusing down on squishy enemy spell casters.
Getting a manta style
would solve this solution. Having enemies such as silencer and treant would be a nuisance because of their ultimates. Manta style would solve that problem because of its active ability as well as give Pangolier extra stats and illusions for the mana drain from diffusal.
Against a physical damage team composition:
Getting an Assault Cuirass
helps Pangolier become more tankier because of the bonus armor and the aura +armor buff he gives to the team, but the minus armor is kind of wasted because of his third ability that's why this item is rarely needed on this hero.
provides a powerful disarm against the enemy carries. Your goal is to shut down any hero in the enemy team, so this item is really viable for Pangolier. The bonus evasion also synergizes with his durability that's why this item is great against physical damage compositions.
Against heroes who rely on active items:
Getting a nullifier
alleviates this problem because of the mute effect it provides, as well as the slow from each hit making Pangolier stick to a target effectively.