Lightwell Slugterra : Season 1 Episode 33

Burpy is sick, and the only thing that will cure him is a trip to the Lightwell - a mysterious, hidden power source only slugs (and the Shadow Clan) know the way to. Burpy can't make it on his own, so Eli vows to take him there. He convinces the Shadow Clan to point the way, but the journey is fraught with peril. Meanwhile the rest of the Shane Gang must fight side by side with the Shadow Clan when Blakk's minions attack.