Today I implemented the first challenge reward! Alex asked for a unique potion card called "Nillo's Elixier of Cunning". It will make a tower of your choice faster and increase its item chance & item quality. I uploaded a first draft of the card below:
[caption id="attachment_558" align="aligncenter" width="200"] Towers will love this potion![/caption]
I think this will be a really useful addition to the game! What do you think? Alex, is this how you imagined the card?