This guide will let you know how to get the Coiling viper in Warframe.
Coiling viper can drop as a reward from doing spy missions on Lua and getting the C rotation rewards.
It is recommended to bring a frame like limbo that can go through or bypass lasers since many lasers in Lua spy missions can get annoying.
To get the C rotation rewards from spy missions, you will need to make sure to get all three data vaults. But out of the rewards in the reward pool, the mod has a higher drop rate than some of the other items. So it shouldn’t take you too long to get the mod unless your luck is bad.