Compatibility of 3.5 and Pathfinder

[evil-frosty]

I have recently picked up the PF Core Rulebook and as I have a lot of supplements and splats for 3.5 I was wondering as to the compatibility between the two, I know how PF is advertised and such but how does that actually transfer in game play?

Obviously after a quick skim you have to use to the base classes of pathfinder, but what about feats and possible prestige classes? And what about base classes that appear in 3.5 but not PF can they actually be converted? In a similar vein what other PF books are a good investment, since I am really liking what I see so far.

[The Glyphstone]

It's extremely easy to convert between the two, though PF to 3.5 is more work than 3.5 to PF. Instead of Grappling modifier, you have a Combat Maneuver Bonus derived from a static equation that you use on grapples, trips, etc., rolling 'to-hit' their Combat Defense instead of their AC. A few skills got condensed and changed, and that's mostly it.

[Sucrose]

Conversion is possible, generally speaking. Main thing missing in Pathfinder, that I can recall, is the Concentration skill, which a few non-spellcasting things relied upon. Other than that, basically everything ports without too many issues.

What would be a good investment depends upon your interests as a gamer. I can't give too many recommendations, as I prefer to stay with the 3.5 system.

Edit: Tentacle ninja'd

[navar100]

Things to watch out for:

Pathfinder consolidated skills. When 3E references a skill, use Pathfinder, easy to figure out. Search -> Perception. Gather Information -> Diplomacy, etc.

The Spell Compendium works fine, but you may need some adjustments. Spells that outright kill should be 10 damage per level. Consider adding a saving throw to some attack spells. For example, Ray Of Clumsiness is Ray of Enfeeblement but attacking Dex. Pathfinder gave Ray of Enfeeblement a fortitude save for half. Ray Of Clumsiness should have one as well.

Prestige classes are ok but change the HD, d4 -> d6, d6 -> d8. In other Pathfinder books they have archetypes which are alternative class features for the base classes. Many mimic 3E Prestige Classes. If you're not getting those books, don't worry about it. If you do get them, choose to taste. All references to Turn/Rebuke undead should now be about Channeling. Anything that uses Smite should change to model the Pathfinder Paladin's Smite Evil.

If Pathfinder has the same feat as 3E, use Pathfinder. Otherwise, the feat works fine. However, if it references a feat Pathfinder has, check out the consequences. For example, Shock Trooper while it can work with Pathfinder's Power Attack isn't as juicy as it once was. In fact, in another book Pathfinder has a feat called Furious Focus that removes the to hit penalty on Power Attack for one attack anyway with no penalty to AC, the main reason people use Shock Trooper. Divine Feats that spend Turn/Rebuke undead attempts instead spend Channeling uses.

[evil-frosty]

It's extremely easy to convert between the two, though PF to 3.5 is more work than 3.5 to PF. Instead of Grappling modifier, you have a Combat Maneuver Bonus derived from a static equation that you use on grapples, trips, etc., rolling 'to-hit' their Combat Defense instead of their AC. A few skills got condensed and changed, and that's mostly it.

I realized that and I love that since it is so nice and simple now.

@Navar
Thank you that was very helpful. And pointed things out that would have gone over my head.

As for the kind of gamer I am, I like tinkering with builds and adapting fluff to whatever I need. And I DM sometimes as well as play. So in general I am wondering what books are truly worth the money on an overall basis.

[eggs]

There are a lot of little details that can be missed in the switch. Grease and flat-footedness, touch attacks and power attack, elemental psionic powers, grab-legal sizes, concentration for potions, and so on. If you're doing something in PF, just be sure to check all the relevant PF materials, no matter how familiar the 3e versions are.

[yougi]

Another thing you want to look out for if you're transferring monsters or NPCs is the number of feats: 3.5 gives a feat every 3rd level, but PF gives one every odd-numbered level.

[GoatBoy]

Some monsters need to be rebuilt, most notably undead, since their HD changed but they gain bonus hit points based on their Charisma modifier.

Converting the artificer to Pathfinder has been the source of many a headache. There is a 3rd party artificer, but, well... no, not really.

All core races received a slight boost in Pathfinder, so many of the +0 LA races from 3.5 no longer measure up. A global -1 to all 3.5 races isn't a perfect solution, but it won't upset the power balance any more than leaving them as-is.

Glaring incompatibilities between the two systems are the except rather than the rule. You will get the hang of it very soon.

[gr8artist]

My group recently switched to pathfinder. Ultimate Magic and Ultimate Combat are nice... they add a lot of feats, spells, and alternate class archetypes. We usually use the Pathfinder SRD anyway.
Pathfinder included a slight (but noticeable) change to skills and what it means to have a class skill. This makes it a lot easier to round out your skills when you're multiclassing. It also means any PrC with a minimum skill rank req. from 3.5 needs to have that amount reduced by 3. (Having 3 ranks in pathfinder is equivalent to 6 ranks in 3.5 for PrC qualifications.)
Our PF group currently contains one Master Thrower, a 3.5 PrC. The extra feats he got during rogue career helped him qualify for it, he took 5 levels in it, and now he's back to rogue for more sneak attack (and bleed).
He's keeping up just fine, if not one of the strongest members in our group. His only weakness is his ammo consumption (10 darts/round)

[navar100]

Re Divine Feats

Both paladins and clerics in 3E could use the feats just fine. However, when using Channeling in Pathfinder paladins have a disadvantage. Paladins have to spend two uses of Lay On Hands to use Channeling, which becomes unnecessarily expensive to use a Divine Feat. I recommend as a House Rule for Divine Feats in Pathfinder to spend Channeling uses or Lay On Hands uses.