Skill test boosting uses the little icons on side of cards. If they match the skill being tested (✳️is wild in this case), then you boost your skill for the test. This is just the Skill Card system from the Arkham Horror LCG, which has a lot of fun design space to play in
ALT Game UI of a Skill Test in a tactical card game: Willpower (3) vs Defense (3)
ALT The same skill test, but an extra card has been added, boosting the test to Willpower (5) vs Defense (3). The additional card reads "If this skill test is successful, draw a card"