Here's a quick PTR FAQ posted by Bashiok.
Official Blizzard Quote:
Q: How do I begin testing on the PTR?
A: When you start Diablo II change your Battle.net gateway to ?ClassicBeta?. When you log in the 1.13 patch will be applied to your game and you can begin testing the changes made in the patch. Since it's a new realm you'll need to create a new account.
Q: I don't see the ClassicBeta realm in my gateway list!
A: Log into one of the other gateways first, then back out and the classicbeta realm will appear.
Q: What if I want to play the normal game again?
A: Simply choose any of the other (non-PTR) gateways. Your game will be reverted to version 1.12 and you?ll be able to play on the live realms as normal.
Q: Where are my characters?
A: The PTR realm is separate from the live realms so your current characters aren?t carried over. You?ll need to create a new character to begin testing. But, cheats are enabled and you may use the following cheats by typing them into chat while in a game:
Gold # - Will provide the amount of gold specified
Level # - Will increase your level to the number specified
Waypoints 1 - Will activate all waypoints. You must still reach an act before that act?s waypoints will be unlocked with this cheat.
Q: What happens to my characters once the PTR testing period ends?
A: They remain on the PTR realm to be removed once the test ends. Characters on the PTR realm won?t transfer to the normal realms.
Q: How long with the PTR run for?
A: As long as we deem necessary to ensure the patch and changes are solid.
Q: Where can I give feedback and what kind of feedback do you want?
A: All 1.13 PTR feedback and bug reports should ONLY be posted in the Diablo II Test Realm Forum here: http://forums.battle.net/board.html?forumId=20601702&sid=3000
- All post should have a subject line that clearly describes the bug or feedback being given
- Use the search feature to ensure a thread doesn?t already exist before posting
- When reporting a bug include as much information as you can, including steps to reproduce it if possible
- Any non-constructive posts may be deleted and the poster?s privilege to post revoked
- This is a chance for you to ensure the 1.13 patch includes changes and balance tweaks that you think would lead to a better overall experience. Getting the information to us in a clear and logical way helps us understand your view and makes it easier for us to collect feedback for any potential updates to the 1.13 patch before release.
Q: What is the new "Mystery" mentioned in the patch notes?
A: It's related to the respec system implemented in the patch and can grant additional respecs beyond the three given for completing the Den of Evil quest in each difficulty. You'll have to play to find out how though.
Here's the new patch notes!
A new Mystery has been revealed!
- Players of Hell Difficulty Realm games are hereby warned once again,
that a series of new and challenging tests await you! The answer lies
within Diablo's Bosses, which span across the world from the Den of Evil
to the Throne of Destruction...
- Fixed an item dupe bug.
- Video improvements for Intel Mac machines with OS 10.5 or greater.
- Uber Mephisto now checks for both Uber Baal and Uber Diablo to be killed before spawning summoned minions (Before he would only check for Uber Baal).
- The game will no longer stop and then restart the game music after the window loses and then regains focus.
- Fixed an issue where the game window would minimize when running in windowed mode when it lost focus.
- Fixed an issue where the game window wouldn't center properly when it was created.
- Respecialization is now possible! Completing the 'Den of Evil' quest will now additionally reward 1 free respec which can be saved. Players who have already completed this quest should receive 1 free respec in Hell difficulty.
- Increased the drop rate of high runes.
- Support for blit scaling in windowed mode. The game can now be maximized to the largest 4:3 resolution supported (hooray widescreen users).
- Some rare drop items now have an orange color. i.e. Runes and items required for Uber Tristam.
- Modified the gold bank limit to be a flat cap not bound by level.
- Nightmare/Hell WilloWisps champions/uniques have had their damage greatly reduced.
- Removed the requirements to create a hardcore character.
- Greatly reduced the explosion damage dealt by Fire Enchanted monsters.
- Uber Mephisto and Uber Baal's summoned minions no longer give experience.
- Removed Oblivion Knight's Iron Maiden curse.
- Hellfire Torch Firestorm proc rate has been reduced to 5%.
- Users can now toggle the display of text over the Health and Mana globes by clicking on the bottom area of each orb.
- Updated two Act 5 mercenary names to Klar and Tryneus.
- When creating a single player game, pressing the 'Enter' key now automatically creates a Hell difficulty game if possible.
- When creating a game, each difficulty button is now bound to a unique key: Normal 'R', Nightmare 'N', and Hell 'H'.
- The 'Enter Chat' Button in the battle.net waiting room is now bound to the 'Enter' key.
- Added the windows system buttons to the game window (MIN, MAX, CLOSE).
- Added new command line parameter '-nofixaspect' which allows users to not fix the aspect ratio to 4:3 when maximizing windowed mode. This lets the game 'stretch' to fill your monitor.
- Added support for '-sndbkg' command line switch. This enables sound in background.
- Added support for '-nosound', '-window', and '-windowed' command line options.
Revised Skill balance for Player Character classes
-Immolation Arrow - Increased radius of Explosion effect by 33% and Immolation effect by 50%.
-Immolation Arrow - Explosion effect damage increased by 20%.
-Immolation Arrow - Increased base duration by 33%.
-Shadow Master - Increased resistance range per point from 5-80 to 5-90.
-Whirlwind - Reduced initial mana cost by 50%.
-Masteries - Changed critical strike chance from 0-25 to 0-35.
-Blessed Hammer - No longer ignores resistances of undead and demons.
-Werebear - Damage bonus increased by 15% across all ranks.
-Werebear - Increased health by 25% and armor by 1% per point.
-Shockwave - Synergy from Maul adds 5% damage per point.
-Blood Golem - Removed negative shared life effect (player no longer loses life when golem takes damage).
-Corpse Explosion - Increased base damage dealt from 60% - 100% to 70% - 120% of corpses health.
-Poison Nova - Increased base damage by 15%.
-Firewall - Synergy receives 1% damage per point of Inferno and Blaze and 4% per point of Warmth.
-Blaze - Synergy receives 2% damage per point of Firewall and 4% per point of Warmth.
-Hydra - Increased base damage by 15% per rank.
-Hydra - Increased base speed of Hydra projectile.
-Hydra - Reduced cooldown by 25%.
-Lightning Mastery - Reduced overall effect by 15%.