I agree and was thinking about this, I was even coming to post this suggestion on the forums. New seasonal mythic dungeons, especially past expansion dungeons should be available as a heroic on LFD when it comes out as a mythic for that season.
The suggestion of asking guild could be helpful, but getting an actual feel for it yourself is a good idea. Being told what to do or expect is one thing, feeling it out on your own internet connection is another thing. Having someone call out what needs to happen might not have it in time if you’ve got a smidge of latency, and a delay from the voice chat transmission itself and then it takes a moment to process the instructions. Doing it at heroic level gives you a chance to learn it without burning up someone’s key if there’s a misunderstanding on timing or some other issue. Having it available as a lower difficulty also offers players the ability to develop quicker reflexes and familiarity to the dungeon.
M+0 to test might not work so well with the older content. You can ignore or never see a lot of mechanics, and depending on the level or class, you could just skip trash mobs that you might otherwise need to know important aspects about killing them if doing the seasonal version of the mythic. I just ran through Karazhan tonight, all of it on M+0 for possible transmog stuff, when I got to Viz’aduum, I killed him before he even left the first platform, he didn’t even get a burning blast out.
The in-game dungeon guides can offer a little insight, but it’s not always sufficient, especially in especially chaotic, high movement situations where you’re also dodging affix effects on top of everything happening in the boss fight itself. For the uninitiated, WoW’s combat system isn’t currently especially good at telegraphing what is happening or even the boundaries of damaging effects. It’s potentially pretty punishing when you don’t know what’s happening - especially with one shot party wiping mechanics which can trigger off of one player’s errors which is especially tedious if the respawn location has a substantial time-sucking run back to the location that the fight was at, which is especially detrimental when there’s a timer ticking.
The heroic mode of older dungeons would have been really useful for folks that did not know either/both wings of Karazhan, if they weren’t familiar or just plain rusty. Karazhan also has trash that has party wiping mechanics if ignored, so people need to be pretty familiar and primed to react as needed. It also gives a chance for players to get familiar with what needs interrupts or other reactive responses.
If Bellular ever gets his wish and we get Skyreach as a seasonal mythic, there’s going to be so many burned keys with problems at each of the bosses and that windy bridge is going to eat loads of players.
Personally I could have used a heroic mode for Mechagon’s dungeons, since I had a break in WoW playing from mid-BfA to about 9.2.5. Even with a dungeon mod like DBM, I made mistakes because I didn’t always know what to expect since stuff isn’t generally well telegraphed in combat for WoW, especially if you’re playing without something like DBM.
It would also be a good source of gear to help prep for mythic, it should drop the same item level as the other heroics at that time. I think it’s a solid idea to implement heroic versions of seasonal mythics on LFD.
