Good / Strong
sober - Serious and thoughtful in mood or behavior, not playful or exaggerated; or not under the influence of alcohol or drugs; clear-minded.
sweeping - Extensive or wide-ranging in effect or scope, having a major impact; far-reaching or thorough.
acute - Very sharp and intense.
steadfast - Loyal and devoted, especially in difficult times.
surefire - Guaranteed to produce a desired result.
impregnable - Unable to be broken into or captured.
viable - Able to survive or live under specific conditions; also feasible or practical to implement
vigil - Staying awake, aware, and watchful at times when it's more usual to sleep.
ingrained - Firmly fixed or established; difficult to change; deeply embedded and hard to remove.
contender - A person or group competing with others trying to achieve the same goal.
operational - Something that is in working order and ready for use.
impervious - Not allowing something to pass through; impenetrable; not affected or influenced by something.