Mercenary

Tactics

 * Because the Mercenary suffers from rather low damage, the Key to mastering him is learning to use your skills not only to damage enemies, but to use the time spent invincible to dodge more powerful attacks. Learn the patterns of bosses and strong opponents and use or  to avoid most damage. Try to utilize the low Cooldown of  on top of abusing your long amount of time spent invincible.
 * A typical combo for the mercenary is to into a group of enemies,  out,  through them and repeat for the remaining dashes followed up by another.
 * You can use to get up to places you might normally not be able to, as it does a small jump.
 * Items that reduced Cooldowns, such as Wicked Ring or Alien Head, are extremely effective on mercenary as they give you the ability to stay invincible nearly indefinitely.
 * Wicked Ring combined with decent critical chance is devastating against Magma Worms since will reset its own Cooldown enabling you to literally climb up a magma worm, dealing incredible amounts of damage.
 * A near-exploit situation can be achieved with a combination of Rusty Jetpacks and Alien Heads causing you to "fly" endlessly using, hovering above enemies and remaining out of reach from their attacks. A demonstration is available here.
 * Like all melee classes, items like Tesla Coil, Toxic Worm, and Barbed Wire help to increase damage output when you're in the thick of the fight.
 * On-hit items, such as the Sticky Bomb and especially the Brilliant Behemoth, work well for Mercenary. and  put out a ton of hits, each of them calculated separately, so you get a lot of chances to activate your bonuses. The Brilliant Behemoth in particular lets you damage entire crowds with.
 * When 2 Wicked Rings are stacked on the Mercenary, It allows him to perform a constant Faux-"screw attack" by bouncing on the heads of enemies with Whirlwind. This greatly increases his ability to remain relevant past the 3rd or 4th stage, Allows him to chain Whirlwind into his massacre consistently, And removes the need for his normal CQB attack.

History
Mercenary