Is 4th edition D&D compatible with 5th edition?

Question

I have all of the hardcover books from D&D 4th edition. I recently bought and am reading the 5th edition players handbook and I must say I like it. I was wondering if 4th edition information (Monster manuals, equipment, spells, and the like) can be used with 5th edition? I have all these books and would hate for them to not be used.

Answer 1

No.

The fifth edition of D&D is effectively an entirely different game from Fourth Edition. While there are some similarities (roll a d20 and add stuff), they tend to be pretty superficial.

Even when names are reused, the concepts underlying the name can be entirely different. For example, a saving throw in Fourth Edition is a difficulty ten roll without modifiers at the end of your turn. In Fifth Edition, it is an ability check usually made at the time something is first affecting you.

With that being said, there is a great deal of overlap in terms of the world (sort of, it's complicated), flavor, and "soft" advice between the two systems. You could certainly use the situations, locations, and characters from Fourth Edition to inspire the same in a Fifth Edition game... You'd just need to throw out all of the Fourth Edition mechanics and rebuild them in 5th edition terms.

Answer 2

No.

To add some detail to AceCalhoon's excellent answer, you can specifically not use the 4th edition Monster Manual for 5th edition. 5th edition uses a much smaller range of numbers from level 1 to maximum level than 4th edition uses. Thus a high level monster of 4th edition has an armor class (Elder Red Dragon AC 40) that a 5th edition character can't possibly hit, because he only gets +6 proficiency bonus at the highest level and +10 stat bonus at the highest possible stat. The same difference in the underlying math of the two editions makes using spells and equipment difficult as well.

Using 4th edition adventures in 5th edition would also be difficult. 4E is mostly balanced around encounters, while 5E is mostly balanced around one day of adventuring. 4E adventures tend to have less encounters, but each encounter is larger with different monster types. 5E adventures tend to have more and smaller encounters.

Answer 3

No.

Let's compare a top-level Fighter.

4th Edition: +22 to hit (or +28 with magical weapon), and about AC35 (maybe AC47 with epic-level magic armour and shields)

5th Edition: +11 to hit (or +14 with magical weapon), AC20 or 21 with a shield (maybe up to AC26 with epic armoury)

We're not just talking about optimization, or PvP. It's worse than that.

Let's put our 4e Fighter up against a monster she has a 50/50 chance of fighting. She needs to roll 10 to hit with attacks, and who needs a 10 to hit her, so the monster has +25TH, AC32. An even fight ignoring class features and hit points.

Our 5e Fighter, against that same monster with +25TH AC32, will need to roll 20 to hit, and will be hit on everything but a natural 1. She'll be slaughtered.

Obviously that's comparing top level, and the effects will be less noticeable at lower levels, but still there.

And then there's the comparison of spells and powers. You cannot mechanically port a 4e character into 5e.

Here's an interesting story: I actually had a 4e campaign written up to level 4, and have changed it into 5e. Very strangely, the main things I've actually had problems with are thematic. As my campaign has a major rebirth-of-the-Primordials theme, the loss of Primal classes made things difficult.

Having said that, I suspect the huge difference in spellcasting would have been the harder jump for me, had I not already run 3.5 games up to 15th level, which 5e is much closer to.

Even though 4th edition characters have much higher numbers for AC and TH and similar, 5th edition spells often have much wider-ranging effects: at higher levels, you're talking about 4e rituals cast in a single action. The control options as well as versatility and utility of casters in combat is much wider than in 4e.

Here's some ideas regarding what you can do to reuse the 4e content you listed:

Monster Manuals

• Find a 5eMM monster with similar power and style, and refluff it. (E.g. take the 5e Orc and pretend it's a Goliath)
• Homebrew it. (Sometimes the line between refluffing and homebrewing is blurred, if you change out a spell or ability or two).

Equipment

• If the weapon or armour gives a +X bonus, halve it. (Many 5e weapons are +0 bonus.)
• Find 5e DMG equivilents.
• Homebrew it.

Powers or Spells

• Ooh, these would be complex. I really haven't attempted it much, I've just found other equivalents. The closest I've come is converting a high-heroic Druid, see below.
• In general, I'd find an existing 5e spell and possibly change the damage type. If you modify spells more, use existing spells as precedent.
• Let's say we have an encounter power which is a big blasty ball of thunder flinging its targets aside.
• Let's change the 5e fireball to have a knockback effect, compare the first level spells burning hands and thunderwave. Thunderwave does 2d8, not 3d6 damage (that's average of 9 instead of 9.5, so not much, but fewer rolls means its less predictable). So our thunderball could do 5d10 damage instead of 8d6 (about the same average but less predictable), adding our knockback/push effect.

Again I haven't had much experience converting powers to spells, so I can only give a few ideas.

PCs and NPCs: some examples from my campaign

• Level 5 Swordmage: I'm homebrewing my own Swordmage class, but I could have used an Eldritch Knight. Maybe I could take the EK, remove heavy armour proficiency, and allow access to spells like Misty Step. Or I could use a multiclass
• Level 7 Druid, specializing in elemental powers. I decided for thematic reasons I want a dedicated Primal class for 5e, and so have been homebrewing an Elementalist. But the class wasn't ready. So I just improvised HP and AC and all that, and said "Right he's got one of this spell, one of this and two of this, then he's down to his mace".

Honestly you can improvise NPC classes most of the time. Calculating things exactly may only make a 10% difference in HP and AC and similar, and it's a lot less hassle. If you're converting a PC, however, you may have to homebrew an archetype or class. Personally, I like doing this (I have 4 settings with 6 homebrew classes and a dozen plus new archetypes... each), but you can always improvise it, refluff an equivalent, or do a half-way switch.

Having converted a character from 3.5 to 4e and now to 5e, honestly, for most characters - that Dwarf mercenary supervising a bunch of orcs just before the boss room, those Killoren fey warlocks who harrass the players on the way to the Keep of Doom - you may as well just improvise that figures. For bosses using PC classes, I would suggest you homebrew it or use another person's homebrew.

5e's archetype system is partially designed for this. The SRD/OGL content just released includes every class and race, but only one archetype and subrace for each: one of the designers stated this is to encourage players to make their own archetypes and subraces.

(I have encountered quite a bit of resistance to this, as 5e's characters are so flexible they should in theory cover everything. 'We don't need a Swordmage, we have the Eldritch Knight' etc. Having said that, classes like Barbarian, Monk and Warlock are pretty specialized. Whether homebrew is necessary is another discussion entirely - I never needed or wanted it in 3.5 but I've found it to be extremely useful in running my old 4e world with 5th edition.)