- UMD is now exclusively a unique feature of rogues, in 5e.
- In 5e, Wizards do not scribe cantrips into their spell books. Spell books do not contain cantrips. You do not prepare cantrips. You cannot learn more cantrips by scribing them. - A wizard could, in theory, write a scroll of a cantrip they know, and another wizard, or another character for whom that cantrip was on their spell list, could use the scroll, but formally speaking, a wizard cannot scribe that scroll into their book or learn the cantrip from the scroll. A DM might allow a wizard to study a cantrip scroll of a cantrip that they didn't know, and eventually learn it (provided they didn't actually cast the cantrip from the scroll and destroy it, and kept it for the express purpose of studying it), but it still would not be recorded in their spell book.
I think you might be misunderstanding some of the things that others have said, Robert. When people say stealth is broken, what they mean is that you can be playing a five hundred pound gorilla in a full one-man band outfit and jumping up and down, screaming at the top of your lungs and banging pots together... and still successfully stealth around you enemies and take the easy advantage of attacking them as an unseen attacker, in this game. There's not even a check involved in doing this - it just works, as long as you step out of their sight cones, which you can check at any time. There is no being 'good' at stealth, because literally everyone is universally godly at it with 100% guaranteed success.
The complaint about phase spiders is that they are, in their 5e stat block, melee teleport junkies who hit and run very effectively, and don't leave themselves vulnerable to attack unless baited into it, or unless characters wait for the right moment. In the game currently, they might warp occasionally, but they stay vulnerable the whole time, and they spit and bleed poison as well for some daft reason.
In both cases, the request is that the game ought to be more like 5e and less what it currently is now. Somehow you've gotten the wrong end of the stick there, so hopefully this clears that up a touch ^.^
