Sentinel

 is a defensive unit  with Stamina whose attacks produce Engineers.

Strategy
Sentinel excels at providing mid-range defense capabilities, with a little attack to put pressure back. For the cost of, it effectively provides and  across three turns, and the delayed. While a bit low-impact, few other units can match that level of defensive and offensive efficiency. Sentinel's ability is equivalent to a Grimbotch (Without the 4th turn threat) and 2 Doomed Drones to outsource buying Engineers to. The final turn gets 1 less soak overall, without the Lifespan weakness. Note that, if better soak and stronger options are in the set, it is efficient to have only 1 Sentinel active at any time, for granularity.

Sentinels excel at providing players with defensive granularity, that is, the ability to efficiently absorb varying amounts of incoming Attack. They also work very well with strategies that might require a large amount of energy or Engineers, such as strategies making heavy use of Electrovores or Tesla Coils. It also has excellent synergy with Galvani Drone. As such, Sentinel is currently the only unit with Stamina with which one might want to attack even though the Attack will be absorbed, simply to get the engineer. Players should avoid this situation by not having Sentinel be one of their first attackers but rather investing in a round of Tarsiers or such first, in order to avoid losing the damage to a simple Wall.

Openings
Player 1 Efficient rush, but can't tech for Walls.
 * DD
 * DD
 * 1) DDA
 * 2) TTC
 * 3) Sentinel +R
 * 4) Sentinel +RE

Player 2 Fast rush, hard to tech for Walls.
 * DD
 * DA
 * 1) TTD
 * 2) TCE
 * 3) Sentinel +R

Change log

 * January 11th, 2019
 * Cost decreased from to.
 * Health reduced from 4 to 3.
 * September 18th, 2015
 * Cost decreased from to.
 * Stamina decreased from to.
 * October 11th, 2014
 * Stamina increased from 3 to 4.