Ye Olde Inn

This is the manticore from Darkworld-



It's one of the biggest figures I have so I've given it totally beastly stats-
Attack - 9
Defend - 9
Move - 9
Mind - 9
Body - 9

Special Rules-
1) The manticore has a venomous attack if a black shield is rolled when it attacks then the hero is envenomed. They must roll 1combat dice each turn and they will lose 1 body point if a skull is rolled. If a black shield is rolled the effects of the venom have worn off. Venom will also be neutralised by a healing potion or spell.
2) If hit all of the Manticores stats are reduced by the number of hits (like an elemental in warhammer).

How might heroes reduce the risk such a creature would pose them?

I was thinking there would be some easy way to kill it that wouldn't involve attacking it directly, but there is a chance the heroes do not discover this method or they fail in setting it up...

Very nice paintjob!
In the Dark World rulebook there was a photo of a painted manticore figure, but it was red (as on the cover illustration). I think your black version looks much better.
In the Dark World rules, the manticore was the strongest monster, too, but could not move on the board like the others, but was restricted to the final stage, so heroes would only encounter it when fully supplied with weapons and items.