ferocious

accentuated, aggravated, concentrated, deepened

emphasized, enhanced, heightened, intensified, magnified

stressed

exhaustive, thorough

harsh, rigorous, severe

barbarous, brutal, savage, vicious

antagonistic, hostile

aggressive, assertive, bellicose, belligerent, combative, contentious, gladiatorial, pugnacious, quarrelsome, truculent

combustible, volatile

agitated, frantic, frenzied, mad

cataclysmal (or cataclysmic), destructive, ruinous

argumentative, assaultive, bellicose, belligerent, brawly, combative, confrontational, discordant, disputatious, feisty, gladiatorial, militant, pugnacious, scrappy, warlike

bare-knuckle (also bare-knuckled), blood-and-guts, in-your-face, take-no-prisoners

menacing, threatening

bestial, brute, inhuman, inhumane

barbaric, uncivilized, wild

heartless, implacable, merciless, pitiless, relentless, ruthless, unrelenting, wanton

bloodthirsty, bloody, homicidal, murdering, murderous, sanguinary, sanguine

rapacious, ravenous, voracious

concentrated, high-pressured, intense, intensive, vehement

excessive, exorbitant, extravagant, extreme, immoderate, inordinate, lavish, overmuch, overweening, unconscionable, undue

crazed, crazy, demented, deranged, insane, irrational, lunatic, mad, maniacal (also maniac)