Each monster has a unique active skill called the Strike Shot which lets them deal extra damage when used. Every monster has to go through a specific amount of turns to activate their Strike Shot. The cooldown for each Strike Shot reduced by 1 for every turn you go through. For individual strike shot cooldowns and a description go to theMonster List

After your monster goes through the set amount of turns, click on your monster to activate your Strike Shot which will then make your monster icon start blinking and have a GO sign above it as shown above.
Aim and release your monster how you do it normally and your Strike Shot will fire.

Each monster has a different Strike Shot name.

Not only does each monster have a different Strike shot name but some Strike Shots perform different actions such as dealing damage, healing your HP, or adding a buff to yourself and/or team.