This build is targeted at a budget player with few resources, allowing them to focus on grabbing up some Endo and farming a handful of Forma. It'll make a mess out of star chart enemies, and can even serve as a first Teralyst [Hunt] weapon while acquiring better suited weapons, without dragging down an entire team in the process.

Four forma are pretty easy to come by, just crack some low tier relics and you're good to go. Since you get this weapon with a Catalyst already installed you don't even need to invest that.

Of course the weapon itself can be had every couple of weeks when Thermia Fracture events pop up. Getting the weapon though, for a tight budget (read f2p) player, could be troublesome solo. If you're intending on getting carried through enough fractures to get the weapon, please ask for a carry before heading to the Vallis. It'll be a lot easier if everyone else knows what to expect.

All of the mods on this build are easy to acquire with a casual farming party. None of them are event driven (not any more anyway) but some may not be in rotation in their potential reward pools ([Argon Scope] from Cambion Drift and [Vigilante Armaments] from Plains of Eidolon). Just wait for the next rotation and check back. You'll get the mods by time you get anywhere near the end of the star chart with a bit of diligence.

Decent places to get these 8 mods are as follows:

Serration - Cambria, Earth (Spy) - 10% chance - Must open all 3 vaults
Hellfire - Coba, Earth (Defense)- Rotation C 7.59% chance
Point Strike - Tier 2 Cetus Bounty - Stage 1 25% and Stage 2 15.08%
Vigilante Armaments - Tier 3 Cetus Bounty - Stage 1 35.19% and Stages 2-3 20.43%
Argon Scope - Tier 4 Necralisk Bounty - Stage 4 20% and Stage 5 33%
Stormbringer - Amalthea, Jupiter (Spy) - 5.56% - Must open at least 2 vaults
Split Chamber - Cholistan, Europa (Excavation) - Rotation B 6.67%
Vital Sense - Valefor, Europa (Excavation) - Rotation B 7.14% chance

NOTE - All but [Vigilante Armaments] and [Argon Scope] can also drop from some enemies if you're lucky! Also, all locations are ordered by availability on the Star Chart.

About 80% of the Endo needed for this gets eaten by [Serration], which is a mod you want to rank up anyway (It's considered a Mandatory Mod for most Primaries). Just rank all of the mods on this build evenly, and once they are all at rank 5, you'll have nearly 3/4 of the total damage output of the build for less than 1/3 of the required Endo and credits.

If you want a different elemental damage type, this build accounts for that, just change one or both elemental damage mods for best results.

The other base elemental mods can be found at the following places (naturally these aren't the only ones, just the places with the highest drop chance):

Cryo Rounds - Lieutenant Lech Kril on War, Mars - 22.92% chance
Infected Clip - Naeglar, Eris - 5.64% chance - Must open 2 caches

You could even remove [Vigilante Armaments] and replace that with a third elemental damage mod since you have enough spare capacity without having to eat a 5th Forma.

Additionally, the forma that are spent won't need to be changed when upgrading to more capacity hungry mods down the road.