Monster Blood IV (Goosebumps #62) R.L. Stine Rare Paperback

IT'S FOUR TIMES AS EVIL!

Evan Ross can't forget about Monster Blood—the evil green slime that never stops growing. It can turn ordinary pets into ferocious animals and twelve-year-old kids into freakish giants. But now there's a new kind of Monster Blood in town. It comes in a can just like the others. Only difference is this slime is blue instead of green. And instead of just growing, it's multiplying—into terrifying blue creatures with razor-sharp teeth...

The final title in the original Goosebumps series.