Synonyms for Mastery:

n.

sensitivity, consciousness, awareness, understanding, lore, Familiarity, information. backing, leadership, greatness, expertness, monopoly, capacity, education, oligopoly. say-so, dominion, jurisdiction, over. act (noun)
subordination.
authority (noun)
command, office, enfranchisement, sovereignty, authority, precedence, clout, sway, commission, credential, license, title, powerfulness, mightiness, faculty, kingship, strength, might, right, prerogative, entitlement, influence, purview, stature, prestige, force, empowerment, charge, potency, primacy, puissance, privilege, power, mandate, birthright, Prepotency, seniority, rank, punch, control, steam.
cognition (noun)
control, command.
command (noun)
grip, management, coordination, will, grasp, government, law, prowess, rule, hold, direction, reign, discipline.
command, expertise (noun)
prowess, adroitness, ability, know-how, proficiency, understanding, finesse, adeptness, knowledge, cunning, grip, Familiarity, power, knack, capacity, cleverness, grasp, skill, deftness, expertness, comprehension, dexterity, genius.
control (noun)
sovereignty, command, dominion, power.
cunning (noun)
wiliness, craftiness, art, smoothness, wariness, Canniness, sharpness, cleverness, subtlety, guile, slipperiness, snakiness, trickiness, sly, deviousness, finesse, slickness, wit, ingeniousness, quickness, foxiness, ingenuity, shrewdness.
influence (noun)
importance, pull, motivation, bias, pressure.
intelligence (noun)
judgment, astuteness, profundity, perspicuity, acumen, sagaciousness, wisdom, sophistication, cogency, intellect, intelligence, erudition, knowledge, comprehension.
knowledge (noun)
expertise.
mastery (noun)
control, supremacy, domination, command, subordination.
power (noun)
vigor, energy.
say-so (noun)
say-so.
skill (noun)
proficiency, adeptness, ability, flair, know-how, talent, deftness, acuity, genius, capability, expertise, technique, knack, facility, adroitness, aptitude, experience, skill, competence, cunning, artfulness, craft, dexterity.
supremacy (noun)
supremacy, domination, predominance, superiority.
victory (noun)
knockout, triumph, achievement, Subdual, grand slam, conquest, success, victory, winning, subjection, ascendancy, win, checkmate.

v.

control (verb)
hegemony.

Other synonyms:

expertness, capacity, say-so. Familiarity, jurisdiction. dominion.