ace in the hole → afraid of your own shadow
ace in the hole (a secret strength or advantage): John seems very confident. He must have an ace in the hole.
Achilles’ heel (the weakest point): She was brave, but fear of cockroach become her Achilles’ heel.
acid test (a crucial test): I have studied hard, and this exam is an acid test for me.
across the board (including to everyone in a group): Our salaries were increased by 10% across the board.
act high and mighty (behave arrogant): The members of the bodybuilding club all act high and mighty so far.
act your age (don’t be childish): Stop making loud noises and act your age!
add fuel to the fire (make a bad situation even worse than it is): Making wrong decision will only add fuel to the fire.
afraid of your own shadow (easily frightened): I can’t imagine Aden as a security guard, in fact he’s afraid of his own shadow.