Underground Spring is a rare structure that slowly gives your base strength at the cost of its own. The strength of Underground Spring can be increased by leveling it up. Underground Spring can work well in decks that benefit from small base-strengthening over time.
Underground Spring's potential lies in its survivability and synergy with strength-giving cards.
Keep in mind that no matter what strength Underground Spring is at, it will always transfer only 1 strength to your base.
Underground Spring is not a very effective card to play when you need to defend, like most structures.
If you can manage it, having multiple Underground Springs on the board at the same time will lead to massive strength gaining.
If this card is played on your enemy's baseline, it's almost always worth ignoring it and attacking elsewhere. The squeeze on your enemy's deployment helps you, and any damage you deal to it is no better than dealing damage to the opponent themselves. If you are playing this card, consider playing it further forward, in order to maintain your frontline at the same time as feeding you life, as any damage it soaks up from attacks is functionally the same as healing passed to you, in the long run.
…remove 1 strength from itself…
…remove 1-2 strength from itself…
…remove 2 strength from itself…
…remove 2-3 strength from itself…
…remove 3 strength from itself…
May 9, 2019: Added to the game
June 27, 2019: Increased strength by 1
November 26, 2019: Increased strength by 1
September 1, 2020: Increased strength at higher levels, increased ability at higher levels