https://imgur.com/a/KpB3Q

Step 0: Get the achievement that reduces your Research cooldown to 1 fight, either by spending 3000 points or having a successful Professor run.

Step 1: Pick the professor and immediately take Portent. Use it and look at what abilities the LoD has; you want the gift demanding ability as his first ability, and you his second ability to be anything but the time limit ability. Everything else you can cope with.

If he has the wrong abilities, simply quit out of your run and start another. Repeat until you find a LoD with the abilities you want.

Step 2: Once the Portent shows you a beatable LoD, take a screenshot of the Portent to remember and exit out of the game without saving.

Step 3: Re-open the game and continue your game - the LoD will remain the same, but you'll be able to pick a different floor 1 talent. Pick Flee.

Step 4: Find a monster on the floor that has a strong card that is good in multiple. Research it, flee, fight another monster to refresh your Research cooldown and repeat as many times as there are monsters on the floor. You can get ten copies of Circle if you find a mid-level Thief. If you're not sure what cards you can steal from a monster, you can always start a fight with them and quit the game if you don't like what you see. Try to always use your Research and Make Camp abilities on cooldown - you can steal 30 cards over the course of your run this way, all of them ridiculously overpowered.

Some cards to look for:

Priests have Focus, Haste, Inspiration, Thieves have Circles, Mages typically have good spells/mana cards and Jasra's Emeralds starting at level 9. Mid level Akami have Solidify, which is the most insane spell in the game (8-mana discard 3 lose 3 actions). Discard is very strong - if you can't find Solidify, Dragon's Roar can be a decent replacement. Soul Crush might look good but usually doesn't work against most monsters.

Try to get cards that draw one or more cards - you should be able to play your entire deck in one go once your circle-chain gets going, while your opponent can't keep a single turn due to your discard. Good sources of damage are a must - look for Dice to go with your Circle chain, Blade Flurry (multiple Blade Flurries stack! Mimic a Blade Flurry for triple damage) or Electrocute/Discharge and lots of mana cards. Overload is good but doesn't seem to be used by any monster. Haste becomes very powerful in multiples, and is very easy to find.

Step 5: Pick up whatever cards/talents you need to deal with the LoD - Deck of Wonders is really good at generating cards you can gift to the LoD, Sublime is good all around and Master Thief is nuts. Pick whatever you need for the floor 2 talent - I like copying the strongest card I have.

This takes a while and doesn't get you any achievements, but it's a lot of fun to dump a 50 card deck onto the table every turn while your opponent discards their entire hand.