Drain

Animals with the Drain ability reduce the opponent's current Energy by a certain amount when they come into play.

Description
The Drain ability reduces the opponent's current Energy by 1 point when played.

It does not seem to be able to reduce opponent's energy below 0, so playing a card with the Drain ability while your opponent is below 1 energy wastes a small portion.

Cards with this Ability

 * Jackrabbit

Strategy
Drain is an ability built to get board control. Low level cards with just Drain require a good Attack and/or Health to be useful just by themselves. Having Drain and another ability, like the Bush Viper, turns that card useful, but Drain will just be an addition rather than its main strength.

The most efective way to use Drain is to build a Control Deck. If your Deck has at least 5 Drain cards, you can fill the board with them in the first turn, making it more difficult to your opponent to use strong expensive cards. However, be sure to fill your Deck with back-up options in case you need them. Also, don't forget that Control decks in this game only work if you have the upper hand: the level of all your cards must be high enough to compete with your opponents, or else your cards won't stand up against your opponent's ones and thus your board advantage will be completely useless.

Notably strong against:
 * An opponent who is trying to regain board control

Notably weak against:
 * An opponent who has board control