Sentinels

Sentinels, as announced in the Update 7 Development Livestream, are robotic companions (pets, if you will) that will follow the players around and assist in various fashions depending on their programming. It is possible to program sentinels with Precepts, or programming cards that can turn a sentinel into an attack drone or a support drone. It can also have many other Mods which, for the most part, look the same.

Sentinels, like Weapons and Warframes, level up with affinity. They have health, shields, armor, a weapon of their own (they cannot use it until a precept is installed), energy reserve and lots of utility. They can be targeted separately from a player's frame and, upon death, do not revive, unless they have a regen mod. Enemies tend to target a frame first but will often target the sentinel instead.

More information regarding the topic will be released as Update 7 is brought live.

Which Sentinel did you start with? Wyrm Shade

Sentinels
There are two kinds of sentinels, each take up two as of yet unknown slots.

Wyrm
Made as an offensive type sentinel, this comes with a laser rifle (which can be upgraded with rifle mods and Orokin Catalyst). When purchased with platinum, Wyrm will also come with Warrior and Crowd Dispersion precepts and a pre-installed Orokin Reactor. The Wyrm is an excellent defense against Nervos as they do enough damage with the Warrior precept to destroy them.

Shade
This is a sentinel for the stealthy. It comes with a burst laser pistol (which can be upgrade with pistols mods and Orokin Catalyst). When purchased with platinum, it also comes with the Revenge and Ghost precepts and a pre-installed Orokin Reactor.

Acquisition
Both Sentinels can be built from the foundry after buying blueprints from the market for 100.000 credits, or bought from the market for 75 Platinum.