Xethreau
Josh Gentry - Author, Wanderer
Game balance by the inclusion of sourcebooks is not a consideration with the term "compatibility." That said, yes, a lot of WotC spells are overpowered because that is the model they work with. (Power creep incentivizes new purchases, much like we see with Magic the Gathering.)
But in terms of raw rules interactions, spells only infrequently experience back-compatibility (even cross-compatibility) issues. Basically, you'll only be looking at specific rules interactions that might fare differently in O5e than from A5e.
Feel free to check out this thread with other backwards-compatibility questions!
www.enworld.org
But in terms of raw rules interactions, spells only infrequently experience back-compatibility (even cross-compatibility) issues. Basically, you'll only be looking at specific rules interactions that might fare differently in O5e than from A5e.
Feel free to check out this thread with other backwards-compatibility questions!

Level Up (A5E) - Xethreau's Unofficial A5e Backward Compatibility Guide
This is a guide for porting in O5e rules and characters for use with A5e. When we talk about Level Up: Advanced Fifth Edition (A5e) and "compatibility" with original Fifth Edition (O5e), there has been a considerable amount of confusion. What is advertised about A5e is that it is "fully...
