You wave the others into hiding spots around the room, turning off your Pip-Boy lights one by one as you crouch behind a hunk of steel & bring up your laser pistol at the ready. Lorraine draws her small revolver, Kain readies his bat in the corner parallel to the entrance, & Todd lifts up a wrench to hurl if needed.

Faint steps grow louder, plodding sounds upon the metal floor, until you're sure whatever it is must be standing right in the path of your raygun. You switch on your Pip-Boy light & blind the thing, stopping it in its tracks.

What an ugly mug, what is that thing? The split second thoughts are replaced by the need for action.
>THREE rolls of 1d20+4 (Agility) to attack the stunned Mutated Amphibian! Calling an aimed shot will increase the DC, but success means greater effects, naturally.