After finishing the new cinematic mod quest, The Teacher. You will be granted a new burst fire rifle called the Thornbak. This weapon is aimed at being a new player weapon and is really good as a status-based gun. But, as far as endgame content is concerned, it will not carry much weight. Below will be our recommended build for a casual/new player in Warframe.
Non-Steel Path Build for Thornbak
Below will be our mod setup for the Thornbak. You will need at least 2 forma and have completed Warframe: 1999 to obtain some of the mods and arcane used:

For starters, make sure the damage booster mods, Serration and Split Chamber (if you do not have Galvanized Chamber, of course), are on this gun at all times. From here, just go with the flow and slot status effects galore onto it. Being able to mix gas, radiation, electricity, and magnetic damage makes it an “all-rounder” gun. Allowing for quick disposal of any and all types of enemies in the game.
Thornbak in Warframe Review
As stated before, this gun is not built to go all the way to Steel Path and beyond, and it doesn’t need to. As a gun that will be granted to new players, it will serve them very well. I am glad this new mod quest was added with The Vallis Undermind. Especially considering it is going to be a gun you do not need to farm for. However, similar to Higasa in Koumei and the Five Fates, I wish there were unique mods for it. Even if Higasa was not a good pick for endgame content, having unique mods for Thornbak would have made it feel more special.