Investment, added in Beta 6.6, is a Spell Card for the Integrity Deck.
It has the effect to copy a random card from your deck to your hand and lower its cost by 2, at the cost of 1G. This means that you actually get a profit of 1G from using this.
You can deploy that card early, able to play a cheap monster right away. Be warned that the card added is random, so you may end up getting a card that costs 0-1G, such as Break, wasting the cost drop of the effect. Though, it isn't that big of a problem due to you also having copied the card.
This card is more effective if your deck specializes in high-costing cards. If you use Lesser Dog before this, you are able to gain a 2G profit from its effect.