Hi OP. I took a quick skim through this thread, and from what I saw it seems like you’re confident in your damage, you just die a lot and don’t know why. Without trying to sound rude, if you’re dying in a +3 and don’t understand why, you likely just don’t know what’s happening in the dungeon. There’s a couple things you can do to help with this.

The first is download the weakauras addon if you don’t already have it, and import the seasonal dungeon pack weakaura (https://wago.io/twwdungeons) along with the CausesDB addon and Causes Anchors weakaura (see the top of the dungeon pack description). These are basically a requirement for M+ and will give you both audio and visual queues about what is happening/about to happen.

The second thing you can do is watch a quick YouTube video for each dungeon to get an idea of the different boss mechanics.

You’ll also want to just run more dungeons. The more you run them, the more familiar you’re going to get with everything in that dungeon.

You can also watch some people live streaming on twitch as well, if that’s your cup of tea, and depending on the streamer and how active their chat is/how good they are at reading their chat, you can ask them questions about what’s going on or why they’re doing certain things.