With each successive hit, you grow in power.
You perform a devastating uppercut that inflicts heavy damage on a single target. So if you normally crit for 100k damage and use a 40% damage buff from Howl, your crits will straight up deal 140k damage. Unlike all other damage bonuses like the extra damage from Strength, Focus and '+X% damage' items/skills, the damage bonus from Howl applies AFTER your entire damage is calculated. The best part of Howl is its damage increase buff. It has no cooldown, lasts for 13 seconds at max rank and slows all enemy movement and attacks to a crawl.
When maxed, its range is sufficient to hit all enemies on screen. One of the best debuffs in the game, if not the best overall. Affected foes are slowed and become less able to defend themselves for several seconds. You howl in fury filling nearby foes with terror. The skill receives great range bonuses with each tier, becoming a highly effective AOE attack. The damage improves with skill rank, while the bleed damage also improves with player level and tier bonuses. The starting Berserker skill, basically a swipe attack. You tear into all enemies directly in front of you, leaving them bleeding for six seconds.