I load up three storage cabinets with cooked meat into a 1x2 Stone room then throw it all out and demolish the cabinets. Pick up all the food after each cabinet and you’ll be way encumbered. This’ll feed the monster for a long time.

If it happens to get out as a baby just stare it down and it should stop wandering. You may be in the stand-off for a while, but this worked for me. Luckily he was over 9% maturation

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