Diablo II: Resurrected 2.4 PTR: Infinite Resources Through Deleting/Restoring Premade Characters

wowhead.com:

Before the cries of «Don't tell Blizzard — they'll nerf this!» start — this feature was mentioned in the official patch notes. However, since many people are complaining on various forums about resource shortages on premade characters, we thought this was worth a highlight. (And for a complete list of everything that's on all premade characters and mules on the PTR, see the following guide.

We did inventory so you don't have to!) All Gear and Items on Premade Characters and Mules on D2:R 2.4 PTR You have several different Runewords you want to make for testing, but you are only given 3 of each Rune on the premade RUNES mule. Certain runes are used repeatedly in the most popular Runewords, so how can you test everything you want to test? Or what if you want to respec a class multiple times — more than what you're given through your free respecs and the 10 Tokens of Absolution? Does this mean you have to go farm the Hell bosses for the needed components? Thankfully, getting infinite resources for all your testing needs is much easier than that. Blizzard made it simple to get all the resources you need to test everything to your heart's content, because all premade characters, including the item mules, can be deleted and recreated at will.

If you find yourself running short on Runes on the RUNES mule, you can move the remaining Runes into your shared stash, delete your RUNES mule and restart the game. It will make a new RUNES mule with its full stash of 99 runes — 3 of each Rune available in the game. This works for all premade characters, including class characters.