Never has the phrase ‘burying the lede’ been more relevant. I did think this was going to be another, simple, “looks like a normal animal but with a twist” Fantastic Beasts.
Blink and you’ll miss the part where fire shoots from your butt.
Murtlap

It’s a water-based rodent. It has a strange growth on its back.
And it can cause a flaming anus with a single bite.
The bite also causes shakes and sweating, but that seems incredibly secondary. I think we can all agree that knowing that at any moment you might become a natural flamethrower would leave anyone trembling.
This is another Fantastic Beast that won’t offer much of a challenge in a D&D fight. What you do have here, is an interesting coastal trap for the unsuspecting hero. The curious warrior upturns a half-buried conch to find a rat attached to it. Ouch! It bit them. Hardly worth worrying about.
Cut to an hour later, when their flatulence is very actually deadly.
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