It is supposed to tell you when you run out of moves and have to draw from the deck. I tried it for the first time yesterday and it didn’t do anything that I noticed.
I just used one to see what it does.
It highlights the deck you draw from when you can’t place any of the cards on the stacks.
If you take you cursor over the boosts it will tell you what it does. That’s how I found out what the spyglass was supposed to do. Apparently I just didn’t notice the deck being highlighted.
Here’s a list of what I have available at this point…
Spare Joker – Have a spare joker next to your deck
Spyglass – Tells you when to draw from the deck
Bonus Fish – Starts your score multiplier at X2
Key Magnet – Attracts all key cards to the top
Mine – Explodes an entire row of cards
Depth Charges – Explodes several cards in a stack, twice
Starrgh-fish – Makes 6 fast moves without breaking your run
Extra Cards – Adds 13 cards and 1 joker to your deck
Extra Time – Adds 30 seconds to the click
Double Mine – Explodes an entire row of cards, twice
Double Time – Doubles the time on the clock
Run Finder – Flips cards face up if they are on a run
Starting Joker – Ensures that you first draw a joker
Extra Jokers – Adds 2 jokers to the deck