Archaeologist
Kill Doctor Bones

I will first describe the conditions on how I found Doctor Bones then I will give you tips on how to make it easier to find him.

My game setup was pre hardmode, medium world, and my location was the jungle surface. First I built a small shelter on the jungle surface with two water candles inside. I spent a couple blood moons and several nights inside my shelter, only going out to kill zombies to allow more to respawn, but still I had no luck. Then in between my search I was using my hellavator and for the first time I found a Nymph in the cavern layer inside the Tundra biome. I killed her and got the Deceiver of Fools achievement. Then the next time I went to the jungle on a normal night, after killing a bunch of zombies, I found Doctor Bones my first try. I found him on the surface, and in the vicinity of my shelter and water candle buff. I will provide a screenshot of my encounter and shelter.

<> He only spawns in the jungle biome.
<> You can only find him at night time.
<> Can be found on the surface or underground
<> You have a greater chance to find him on a blood moon, though I found him on a normal night.
<> Water candle increases spawn rate and spawn amount. It can be stacked with battle potion.
<> The battle potion increases spawn rate by 50% and max enemy cap by 100%.
<> Killing 70-100 zombies increases the chance to find him.
<> The Lifeform Analyzer is an accessory that displays the name of rare monsters and undiscovered NPCs around the player. It is purchased from the Traveling Merchant for 5 gold. This can make him easier to see at nighttime and amongst zombies.
<> He cannot jump.
<> I would highly suggest finding him in pre hardmode, because its much harder to find him in hardmode.
<> He has 500 HP and is not that hard to kill.

I hope this guide helps you and best of luck!