This isn't going to be about a full conversion. Mostly because I feel the best conversions are done in situ by the GM.
Today I want to talk about converting one of my D&D 5e campaigns, "Into the Nentir Vale."
A bit of background. Into the Nentir Vale began as, obviously enough, a D&D 4e game. I ran the intro adventures for it with a group, and the reactions were mixed. I tried again with some Pathfinder, a one-shot, but it never quite jelled the way I wanted it to. Fast forward a few years, and D&D 5 was released. I did a series of posts on sunk cost analysis/bias and conversions leading up to it:
Once these were all done, the adventures went on under 5e. Well...we know how this will turn out.
Somehow it seems fitting that I am converting it again to Pathfinder, this time 2e.
The adventures themselves are the HPE adventures from D&D 4e. Essentially I am removing about 1/3 of the content to make it play a bit faster. I am scaling the monsters and encounters to fit a 20th level maximum (vs. a 30th-level one), but in many ways, the conversion between 4e and Pathfinder 2e is easier than converting between D&D 4e and D&D 5e.
The Character: Rowan McGowan
Rowan is my test character here. She is a reoccurring NPC and one I used as my internal tests of various combat situations.
Like the campaign itself, Rowan has seen some history and conversions. She began life as a witch for D&D 3.5. Her concept is a "Witch Knight" or "Witch Guardian." This is a witch that takes up the sword to protect others, typically of their faith and/or other witches. Rowan is a protector of the "Old Faith." Some of her exploits found a home in my Pagan Witch book, for example.
In D&D 5, Rowan was a multi-classed Warlock (Hexblade)/Paladin. Her background was an acolyte to cover her growing up in a religious order of witches. She picked up the blade when she saw others of her kind being killed. Her devotion is like a Paladin, just to a different cause. Multi-classing her was pretty easy to do since Charisma is the prime ability of both Warlocks and Paladins.
When converting her to Pathfinder there were a number of key differences.
First, while warlock was a compromise in D&D 5 (I wanted a core book class) I can do a proper witch in Pathfinder. But witch's main ability is Intelligence in Pathfinder (though I will argue with some authority that it should be Charisma). Also Pathfinder 2e does multiclassing VERY differently than what D&D 3.x/Pathfinder and D&D 5e do it. Interestingly enough, it is more similar to how D&D 4 did it.
In 5e Rowan's first level was Warlock (Witch) and then she took a level in Paladin. I have been leapfroging the classes. She is level 4 now with 2 levels in both Warlock and Paladin.
In Pathfinder Her class is Witch. I had her take Weapon Proficiency at level 1 so she could use simple weapons. At level 2 she is still a witch but I had her take the Champion Dedication feat. This "multi-classes" her into Champion, the Pathfinder version of a Paladin. This is similar to the Multi-class feats of 4e.
Here she continues to 4th level.
The progression is more straightforward in Pathfinder with fewer options in the beginning. The progression in 5e is less straightforward with lots of options. 5e Rowan has more spells for example, but her maximum casting choices will be limited at higher levels. Pathfinder Rowan will have access to much more powerful witch spells, even if she has fewer right now.
Rowan McGowanWitch 4
Chaotic Good
Medium
Human
Versatile Heritage
Humanoid
Perception +7;
Languages Common, Draconic, Elven
Skills Acrobatics +1, Arcana +9, Athletics +4, Diplomacy +10, Intimidation +10, Lore: Scribing +7, Occultism +7, Religion +7, Society +7, Survival +7
Str +4, Dex +1, Con +0, Int +1, Wis +1, Cha +4
Items Half Plate
AC 22; Fort +6, Ref +7, Will +9
HP 32
Speed 20 feet
Melee Greatsword +10 (Versatile P), Damage 1d12+4 S
Devoted Guardian 
Requirements Your last action was to Raise a Shield. You adopt a wide stance, ready to defend both yourself and your chosen ward. Select one adjacent creature. As long as your shield is raised and the creature remains adjacent to you, the creature gains a +1 circumstance bonus to their AC, or a +2 circumstance bonus if the shield you raised was a tower shield.
Occult Prepared Spells DC 17, attack +7; 2nd ; 1st Command, Mage Armor; Cantrips Chill Touch, Daze, Mage Hand, Read Aura, Protect Companion
Arcane Innate Spells DC 20, attack +10; Cantrips Detect Magic
Arcane Innate Spells DC 20, attack +10; Cantrips Shield
Focus Spells (1 points) Pact Broker Range 30 feet; Targets 1 creature Saving Throw Will; Duration sustained up to 1 minute You offer to broker a pact of peace. If the target accepts and doesn't take hostile actions against you and your allies, you take a –1 status penalty to Deception checks to Lie to them. If they refuse and take a hostile action against you or an ally, they must attempt a Will save. If they accepted the offer and then take a hostile action against you or an ally, they must attempt a Will save and treat the result as one category worse. Regardless of the outcome, the target is then temporarily immune for 1 minute. Success The target is unaffected. Failure The target takes a –1 status penalty to attack and damage rolls against you and your allies. Critical Failure The target takes a –2 status penalty to attack and damage rolls against you and your allies.
Phase Familiar 
Range 60 feet; Targets your familiar You draw upon your patron's power to momentarily shift your familiar from its solid, physical form into an ephemeral version of itself shaped of mist. Your familiar gains resistance 5 to all damage and is immune to precision damage. These apply only against the triggering damage. Heightened (+1) Increase the resistance by 2.
Additional Feats Arcane Sense, Arcane Tattoos, Champion Dedication, Root Magic, Student of the Canon
Additional Specials Arcane Tattoo (Shield), Champion Archetype Cause (Liberator Cause), Familiar, Hexes, Patron (Pacts), Tenets of Good, Witch Spellcasting
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Thankfully I still had her PDF from D&D Beyond.
There are subtle differences to be sure. Pathfinder Rowan has better AC and HP compared to her D&D 5 counterpart on paper. I am not sure if those will make much of a difference though in play.
I knew 5e (and 3.5s) Rowan had a tattoo on her shoulder blade but I was not certain of what yet. In Pathfinder I figure it is the symbol of her Goddess Desna.
While putting these sheets in her folder I noticed I had also started AD&D 2nd Ed, Castles & Crusades, and DragonAGE versions of her started as well!
The conversion was pretty fast, to be honest. These systems still share DNA. In many ways, the Pathfinder version is much closer to my original concept of her so I am pretty happy about that. I will need to see how I can convert the other characters now.
Converting monsters will just be a one-for-one swap out.
