5.5e Changes You’ll Actually Notice at the Table
The two rules changes most likely to affect your next session are the long rest interruption system and the one-spell-slot-per-turn limit, and they pull in completely opposite directions. One is a genuine quality-of-life improvement. The other is going to cause arguments.
Resting Gets Smarter (Mostly)
Long rests now have explicit interruption conditions: rolling initiative, taking damage, or casting a non-cantrip spell breaks the rest. That sounds punishing, but the companion rule softens it considerably. An interrupted long rest can be resumed rather than restarted, with just one hour added to the total. For groups who already run watch rotations and narrative camp scenes, this is less a rule change and more a formal blessing of what you were probably already doing.
The more interesting wrinkle is what the interruption conditions create mechanically. If your scout hears something in the dark during a watch, casting a spell to investigate ends the party’s rest. That’s a real decision, and it gives escalating danger during a camp scene actual teeth beyond “roll for a random encounter.”
The One-Slot-Per-Turn Rule Is Worth Watching
The one-spell-slot-per-turn ruling is the genuinely contentious one. Under the new system, you cannot spend a spell slot on both your turn and your reaction in the same round. Counterspell becomes a genuine tactical cost, not a freebie safety net. Sorcerers using Quickened Spell lose their ability to also cast a leveled spell on the same turn, which guts one of the core fantasies of the subclass.
The intent is obvious: close the gap between spellcasters and martial classes without buffing the martials. It is the less interesting way to solve that problem. The better fix has always been tightening the spell slot economy at the DM level, running more encounters between long rests, or building situations where resting carries narrative cost. A blanket per-turn restriction penalizes clever play rather than resource management.
The Smaller Changes Worth Noting
Potions are now officially a bonus action to drink or administer, which most tables were already doing by house rule. The exhaustion table has been replaced entirely with a flat penalty: minus twice your exhaustion level to all d20 tests, and minus five feet of speed per level. Cleaner, less dramatic. The old table had a certain weight to it when you watched someone hit level 4 exhaustion and realize they could barely function. That feeling is gone.
Diseases have been quietly folded into a new category called magical contagions, all of which inflict the poisoned condition. Lesser Restoration no longer says “cure disease” because, functionally, it no longer needs to. If you were one of the DMs actually using Cackle Fever, you now have a renamed version of the same three example effects.
One genuinely nice addition: sign language is now a standard language, and magic items with command words can be activated using it. In an area of magical silence, a character who knows sign language can still trigger their gear. That is a small thing that will matter a lot at exactly the right moment.