World of Van Helsing: Deathtrap

You must be level 10 in order to join versus matches.

The easiest way to do this is have the person that is losing host the matches. As soon as the round starts the hosting player will be the defender. Press the view button and then the menu button to start the first wave and then press the menu button and select surrender. The match will take about 6 seconds to play.

As the cheevo says simply win 20 matches in versus mode.
Easiest done by boosting with a partner.
If boosting let the attacking team win then neither player has to do anything after host has started the game as the attackers will automatically storm the enemy Base and win.

EDIT: was reminded by xxx AL that I forgot to add in that in order to unlock vs mode your character must be level 10 minimum.

The best way to do this without boosting is to just host the matches and make them public, it will randomly put searching players into your game and you will always be on the defending side (which is literally impossible to lose on the defending side if you build even remotely decent). I put an ice field and frost pillar right by the portal to start and max the slow on both of them, then ice fields on the middle and left lane with slow fully maxed in the first round with acid geysers, gun sentrys and frost pillars. Gun sentrys fully maxed, acid geysers max vulnerability stat, ice fields max slow and frost pillars max slow. Once right lane opens up in the right lane put another maxed out gun sentry there and another max slow ice field. You can also place a razor launcher if you think your dps is too low for the armored enemies. After that just place the same stuff in the back right corner and then spread the rest of your essence out. I wen't 20-0 in versus without boosting building like this. It is also good to note that level and trap points you have accumulated from the campaign DO affect your versus defend game as silly as that is. Good luck.