Aside from the usual sneak and kill with a silent weapon, Warframe has two other means to achieve stealth kills: buff and debuff.
Basically either you do something to your frame, like invisibility (a buff) that helps you perform stealth kills or you debuff the enemies, like blind, to perform stealth kills or finishers.
Most people know that stealth is Loki, hands down, the goal of this article is to introduce other possibilities.
Buff Your Way to Stealth Kills
This is the easiest and most popular way to kill enemies without alerting others. basically you use a buss like Loki's invisibility or Ash's Smoke Bomb to help you get stealth kills. Wukong and Ivara also do well in this department.Group Composition and Team Synergy
Buff frames are often solitary or go in homogeneous groups. An all Loki group is a common thing occurrence in spy sorties. This means you can't bring an EV Trinity or a Slow Nova to help out, you just have the frames that can go inviz.If you go solo often, you probably need a Loki of your own. it's a good investment.
Although frames, like Ivara, do exist and allow for team synergy, these are very difficult to use in a group especially without coordination. An ash with Smoke Shadow also requires a lot of coordination to pull off.
Restrictions
This type of frame is more suited to missions with a non defensive goal, like Spy, Exterminate, Sabotage, Capture, etc. These froames, when modded for stealth have difficulty with defensive objectives like... Defense or Mobile Defense.There are no race restrictions, as long as you don't step inside a Nullifier field/bubble. So you'll find it as easy to sneak past the Corpus as you would the Grineer, Sentient or the Infested.
Conclusions
This method of doing stealth kills is pretty straight forward and easy to achieve. If you like to solo levels, then this is the stealth method for you. You just need to bring a different frame/loadout for def/mob def missions.Debuff Your Way to Stealth Kills
This Method is more uncommon. It basically exists because of frames like Mirage and Excalibur (blind) and others like Equinox and Ivara (sleep). It's more difficult to pull off and requires varying degrees of coordination.
Group Composition and Team Synergy
Unlike the buff frames mentioned above, the debuff frames thrive in non-homogeneous teams. So you can have an EV Trinity, a Slow Nova and a random damage dealer in your team.This will allow you to complete more complex objectives as in trials.
I suggest that once you have your staples set up, you can start looking into a complex play style with more varied team compositions and get one of these frames (most likely a Mirage) unless your preference/play style requires you to choose something else.
Restrictions
Here's where all the complications come in. These types of frames will generally perform poorly against the Corpus and Corrupted, because of Nullifiers/Corrupted Nullifiers.Unlike buff frames, even if you do not go inside a Nullifier field/bubble, the enemies inside these will be unaffected by your debuff and will be able to shoot you, raise the alarm, etc.
Another restriction is that if you cast blind near a Spy site, it'll automatically trigger the alarms. This is something I discovered in the middle of a Sortie so... I just want to pass on the message.
Conclusions
Although not as effective as the more common buff method of going stealth, debuffing does allow more varied team compositions that then lead to the ability to accomplish more complex goals.Final Notes
My personal Recommendation is to get a Loki first, then get used to the mechanics before you go into a Blind Mirage and start stealth farm runs with other people.Remember, you need to develop your mod and weapon collection to be successful at stealth killing or sneaking.
Thanks for reading.
