Honestly, I dont know too much about Lamotrigine, but i just looked it up and it says its prescribed as an anti-convulsant for people who have seizures or who are epileptic and potentially could have a seizure...
So i'm not really sure why youd wanna take this medication, considering it is non-narcotic and won't add anything to your high.
But if you do intend to take it, I dont believe its counterindicated with opioids, and therefore you should be fine.
Do some research beforehand though because, like I said, I am unfamiliar with this drug.