We were not the first who killed Ragnaros in one tank. Maybe we're the first one who killed it in protwarrior. Perhaps the first who posted the video with the tank PoV.
Some words about tactic. When we began to explore Ragnaros, we ran into a dps for the third phase. Sometimes we got 2 meteors on it. Sometimes we could not pass the second transition phase due to low dps.
One of the Insignia's members suggested me to kill Ragnaros with one tank. After the first pool, we realized that we kill it so.
Now I'm writing about the passage of the boss in one tank:
1) In one tank kill is more convenient. dps if higher, all phases are shorter (for example, you'll have only three magma-traps on first, one meteor on third, in every case)
2) Dot falls from the tank on the transitions, during improved sulfuras and roots. Sometimes fall off and the middle phase, if your tank is lucky.
3) the complexities of heal the tank are on the 2nd phase - the second seeding and heal in the "world in flames". Sometimes my cat heals our tank in this moment. Tank have to use shield wall here. And you should drop boss below 40% during second "world in flames", in order to get tank without any stacks of DoT on the second transition phase.
4) To implement the "one tank strategy", tank itself has no room for error, he must calculate the use of his cooldowns for seconds (the video shows it all), the second heal must help the first during "world in flames" and in the end of the third phase.
5) Meteor have pushed mainly heals.
6) If the roots appear in the fire, the cat (firefighter) dragged boss there. If the roots appear in a boss, tank jumped out and led boss away. Then, at the right time frostdk put the boss in the roots.
7) Total it took us 78 attempts, of which 10 or 11 - had a wipe in 4th phase with 4-10% of the boss at the end. When we got lucky with the roots and the fire - the boss was killed.
Now we are killing Ragnaros with 2-3 new people every week. The boss becomes simple after parsing all the nuances of the battle.
Gz to everyone who has already killed him, and good luck to anyone who tries to do the same