There are too kinds of power ups in Final hour, short term and long term.
Short term powerups are instantanius where as long term powerups generally last for about 30 seconds.
5.1. Max ammo
Max ammo is fairely self explanitory. Your weapons are refilled with ammo and you’re given a full reserve.
this happens for every weapon you currently hold.
This powerup is announced by a voice shouting: “max ammo!”
5.2. Instakill
Instakill means that hitting zombies, no matter the health will kill it directly. Instakill lasts 30 seconds and is indicated by a voice shouting “instakill”.
When the time is up, you hear a clear sound.
5.3. Double Points
Double points is also fairely self-explanitory. For 30 seconds each kill will give you double points, again, announced by a voice shouting: “double points” and ended with a clear sound.