I'm having trouble understanding exactly how and why one would infuse weapons.

In Destiny, Infusing is the act of taking a powerful gun or piece of gear and dismantling it to boost a weaker one.

By the time you're facing the challenges of Destiny's endgame, you will be finding guns and armor whose perks will be too valuable to simply discard, even if the gear has lower attack/defense value than other loot you're finding in strikes or from drops.

Just to hammer it home, an example:

I'm using a 290 Red Death, an exotic pulse rifle that gives me health on each kill. I get a random primary weapon to drop at 300 attack. Instead of being forced to use the random primary and leave behind the massive benefit of the Red Death, I can simply feed the 300 gun to the 290 one. Upon doing so, I'll lose the original 300 primary, and the Red Death's attack value will go from 290 to 298.

Specifically, once you hit level 40 on a character the loot grind loop will be something like this:

1. Get legendary / exotic gear for all slots, likely at a damage / armor value far below 300.

2. Get blue engrams from random drops and decrypt them. The gears' values you get when decrypting engrams depends on your light level, so make sure to be at your highest light level when decrypting.

3. Hopefully you'll get blue gear with a higher value than your legendary / exotic in whatever slot.

4. Infuse the legendary / exotic.

5. Repeat.

I believe blues can only drop up to 300 so once you're dealing with raid gear there's no real way to easily upgrade it besides getting more raid gear.

Also, once your light level is >=300 you have a chance for exotic engrams to be decrypted with 310 damage / armor, and once it's >= 310 they're guaranteed to be 310.

Note that infusing exotics is a huge pain in the ass because it requires an Exotic Shard, which are pretty rare (you can only get them by dismantling other exotic weapons, afaik).

Infusing legendaries is much more feasible because it just requires 3 Legendary Marks, and you can get 30 of those every day guaranteed.

Exotic shards are rare? There was a point where I had over two hundred... I guess I'm a special case though.

@liquidprince: Yeah, I went into this DLC with a similar amount thinking I had a ton. I noticed the other day I was somehow down to around 55. Apparently I've been Exotic Infusing a bit...

@liquidprince: Xur no longer sells exotic shards for a relatively low Strange Coin cost, so the only real way to get shards is to get lucky with Three of Coins grinding or buying exotics from Xur just to dismantle them.

Just buy a bunch of year 1 exotics and dismantle them

@jonny_anonymous: That wouldn't help you if you are talking about buying them from the Kiosk. They require an Exotic Shard to purchase, so the only thing that helps is basically you are paying 2,500 glimmer for 3-5 weapon's parts. You can just purchase garbage gear from Xur for 13 strange coins and dismantle, but Strange Coins are now pretty hard to come by too. The cheapest, but most time consuming way would be to run the old Raid's on Hard 3x a week to dismantle any Exotics for their shards.

The thing I don't like about the infusion system is that it was a little shortsighted of Bungie. I'm constantly getting better gear that I want to infuse into stuff. But that requires Armor Parts, Weapon Parts, Exotic Shards, and Motes of Light. Motes of Light seem easy to come by, especially considering half my weapon Engrams decrypt into Motes, but I'm constantly running out of Weapon and Armor Parts because I'm using said Weapons to infuse or my other blues only turn into 1-2 Weapons Parts each. With every Infusion taking 10 Weapon or Armor Parts and leveling up every Legendary taking 15 Parts and Exotic takes 30 Parts, they run out extremely quickly. This has made me destroy pretty much my entire stock of Year 1 weapons that I would have rather kept just because I needed the Parts to infuse things. I hope they fix this in the future by drastically increasing the drop rate of Weapons and Armor Parts from Rare weapons and armor. As it stands all they have done is reduce that drop rate in a patch a month ago or so. If they have to remove the ability to use Weapons and Armor Parts to level up Factions I'm perfectly fine with that. I just need Parts.

@hestilllives19: Huh didn't weapons only cost marks at one point?

@jonny_anonymous: That is only for the new weapons you owned in Year 1 and don't own in Year 2, and they cost 150 Marks, but once you own them they are 1 Exotic Shard and 2,500 glimmer to repurchase. Basically this is to allow you to dismantle that Exotic and rebuy the blueprint at a later date. Or in many cases, like I ran into the other day, to infuse a new Exotic that dropped at 310 that you don't want to use, and to buy the 280 variant cheeply and use the 310 power of Infusion for a needed other weapon.