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Once you get through the maw, you find a large underground cave that appears to be a dead end. The area's rocky surface drops into what appears to be a very shallow lake, insufficient for swimming. You turn to your guide, who disappears in a flash of light. The guide's form is gone, but you hear another voice.
"You have been chosen to undergo the test. I hope you have prepared well - the Guardians of this cove are a crafty duo. Do not think mere force alone will be sufficient. They will wait calmly and exploit any flaws in your strategy. Pass this trial, and you will have a chance at something truly amazing."
Only Rain has the raw materials to be summoned. All other weathers are not allowed. Water source available. Neither Dig nor Dive can be used.
Guardian Actions: Metang: Meteor Mash Eel Stew -> Bulldoze
Eelektrik: Gastro Acid Eel Stew -> Thunderbolt Eel Stew
You haven't lost yet, but both of your Pokemon are in the red and the Guardians are still in decent shape. This looks like the end...
(By the way, I forgot about Shield Dust during the Nest encounter, so Thor shouldn't have been paralyzed by Spark at all during that part of your run. Unfortunately, you didn't catch it, either, and it's too late for me to fix it, so you're stuck with it.)
Metang: Bulldoze -> Bulldoze; if Thor uses Magnet Rise on Action 1, change that action to Zen Headbutt Thor; if Thor has fainted already, change that action to Zen Headbutt Eel Stew
Eelektrik: Thrash -> Thrash
Thor runs himself out of energy, leaving poor Eel Stew to be turned into eel stew by a Thrash from the Eelektrik. Returning your fainted Pokemon, you make a mad dash out of the cove, trying to put as much distance between yourself and the Guardians as possible. The voice speaks to you one last time as you hurry out the entrance:
"You have seen the sort of experiences that await you in The Legend Run. You would be wise to never attempt one again. Should you be foolhardy enough to try once more, I will be waiting; but next time, you had best come more prepared..."
You had a good run; I definitely could have played better in a few places, but this was my first TLR reffing, so don't judge me! Assuming you want to claim Tynamo and Ledyba, you may claim them as you would if you had bought them (nature of your choice, blank EC/MC/DC, Level-Up moves to 25, 3 Egg moves, and 3 TM moves). I look forward to reffing you again!