Within the context of Classic, the method most frequently proposed is to re-tune bosses to make them harder. Rather than copying the numbers, re-create the relative difficulty. Kind of like, when you first start working out, you use small weights. When you get stronger, you lift bigger weights. The WoW community is more knowledgeable, more experienced, has better hardware, etc. We're "stronger." So give us tougher bosses. There are a lot of forms that could take. Bosses were constantly re-tuned during vanilla anyway, so if Ragnaros does 10% more damage or something, is that really a problem? I don't think it is. What about resistance gear? back in the day, collecting resist gear was a thing people did. But the numbers and strategies are so well known today that only the tank really needs it anymore. Bosses could be re-tuned with more resistible elemental damage so that's important for entire raids to gear appropriately. That would be entirely keeping with the spirit of vanilla even if the actually numbers sitting in a database somewhere were different than they were ~13 years ago. If you want to go a little farther, a few people have proposed adding new abilities to old bosses, adjusting their timing, etc.
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Bioelectric Blast (Deadly) - Blasts the target area with electricity. Inflicts 65,654 Nature damage to enemies within 8 yards of the impact and creates a patch of Electrified Ground. Electrified Ground inflicts 14,882 Nature damage every 2 sec to players within it. Shock Burst (Important) - Inflicts 4,377 Nature damage every 2 sec for 12 sec. Upon expiration, strikes all players, inflicting up to 26,261 Nature damage. This damage is reduced the further away players are from the blast. Electric Discharge (Healer Alert) - Wekemara discharges electricity from itself. Inflicts 13,131 Nature damage that chains to additional targets every 1.5 sec. Submerge - Upon reaching 50% health, Wekamara will submerge and summon Spawns of Wekamara. Electrified Splash - While submerged, Wekemara rains electrified water from its pool. Inflicts 21,885 Nature damage to enemies within 3 yards of the impact area. Spawn of Wekemara (Damage Dealer / Tank Alert) Charged Bite - Inflicts Nature damage to an enemy Conductive Spittle - Inflicts Nature damage to an enemy and increases Nature damage taken by 50% for 16 sec. Loot Tables
The upcoming stress test will have some limitations. If you’re accepted for the test, you’ll see the launcher offer you a new drop down on the World of Warcraft section marked as “Beta & Stress Test: WoW Classic” which will allow you to download the client in advance of Wednesday’s test, but if you’re not already in the beta you won’t be able to log in until May 22 from 4 to 6 PM Pacific time. If you’re already in the beta, be aware that you won’t be able to log onto the beta realms either, as those will be down while the new stress test realm is up. The purpose is to get as many players as possible into those starting zones to test for stability — so there are some limitations.

Along with revealing the WoW Classic release date, Blizzard also listed plans for both a beta and stress test of the game. Players who opt-in for the testing on their account manager page and have an active subscription will be randomly selected for the beta starting May 15. Then the developer will have three stress tests where players can log in to play the game for a short period of time on the following dates:
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