The Principle of Inverted Reasoning

I'm curious as to why you think this way. Do you leave Nether Blast at level 1? If you don't, then casting your level 3 Nether Blast at level 5 would deplete almost 1/5 of your mana pool, with no way to regenerate it if you consistantly do your "focus fire harassment" without a mana regeneration item like Ring of Basilius. Magic Stick or Magic Wand would only give you enough mana to cast the spell 1 more time even with full charges, and will not solve mana problems unless there is an enemy Bristleback on your lane.

Hmm, ring of basilus/aquila might be a good idea cause of the damage + mana regen. I'll agree with that, but you know, that or wand or both.

It's also important to remember that the sole reason why pugna is considered a support is because of his ability to damage towers, in which case, he supports the team by bringing in gold.

It's interesting how it supports in an indirect and offense manner.

OHMYGODDIDKYFOIDJUSTAGREEWITHPORYGON.

Well, I myself would ask these to myself at the start of a game:
1) Do I want to win?
2) What do I have to do to win?
3) What do my teammates have to do to win?
4) What do our opponents have to do to win?
5) How do we prevent our opponents from doing that?
6) How do we prevent our opponents preventing us from doing what we have to do to win?

These actually work well. These can be seen from your picks and the enemy picks, and will guide you throughout the game. Never forget to adapt to situations though.

Optionally, you could ask yourself if you want to have fun. If your answer is yes, by all means do whatever you want.

inb4lock

Now we're getting to something. Technically, Pugna isn't a true support, since he needs some survivability items to counteract his low strength gain. He can still act as a semi-support if needed, getting a couple of wards here and there if your team's supports cannot afford it. I'll also agree to Dagon on Pugna. It acts as a huge nuke combined with Decreptify, and can help bring down an enemy carry pretty quickly (just make sure not to KS too much). However, getting one means that your team has less survivability in teamfights and your team will struggle against tanky opponents sometimes. Veil of Discord is awesome on Pugna paired with his Nether Blast and Life Drain as well. Also Aghanim's Scepter. Don't skip this one, trust me its good.

Basically, Pugna is a hero where you can get all the items that you don't get on the other heroes you mentioned, and he also does really well with them.

Like for example, Luna, considered a carry and not a support, yet has a damage aura.. so I would more likely get support items on her then pugna.

Such as, the headress at start because raw damage and life regen at start are basic powerful things.

You could get ***uult cuirass to go along with the damage, dominator to control the creep that yields +30% damage aura, it all works together.

but those would be items got after stuff like dischord, algeimz soul ring etc.

Dominator should generally be gotten early. It really helps her survive.

Oh, and everything you mentioned was possible except soul ring.

Closed.

I think the reason is obvious.