1. Each of the four previous answers is in its respective deck. Each letter of the answer is surrounded by a ring of eight (seemingly random) letters. So that means the first letter of each answer is in the second column, second row of its deck.
2. Translating each of those center letters into semaphore, you can extract two new letters. By circling (or highlighting) those and reading them in order, left-to-right, top-to-bottom, you’ll get two words or phrases in each deck.
3. Solution: Deck 4: COFFEEMUG / PINTGLASS, Deck 3: BICYCLE / GIRAFFE, Deck 2: NEPTUNE / GLASSES, Deck 1: CLUB / PAWN
4. Following the instructions leads you to make four semaphore signs. When interpreted by a teammate, they read WAVE.