This guide is designed to get you on the exact spot you will need to be in order to get these achievements. I highly recommend you use something like gw2stuff.com in order to keep track of event timers, as some of these assume you are already arriving to the location of the various bosses. It's also highly recommended you consider doing these on a more populated server, or with a coordinated guild effort as some like “That Had to Burn” and “Don't Feed the Beast” involve a higher level of coordination.
Don't Feed the Beast
This event starts in Caledon Forest, just next to the Falias Thorp Waypoint. You'll need to speak with “Gamarien”, who start an escort pre-event, and starts “The Battle for Wychmire Swamp” meta-event chain.
Go through his event, and a couple of other's, until the Great Jungle Wurm starts. This is where your work for this achievement starts. Occasionally some Husks will stroll up, marked with crossed swords over their head, who you need to keep from the Jungle Wurm.
Use all the CC possible to keep them from advancing on the Jungle Wurm and burst them down.
Typically having a large enough group will make this achievement a non-issue.
In more populated servers this achievement, which is tied to the Shadow Behemoth in Queen's Dale, is a non-issue considering the mass of people that generally get involved with this, especially after daily reset.
If you're with a smaller group of people, about 3 people per portal should be sufficient enough to burn them down as soon as hey come up. Focus ONLY on the portals and you won't have an issue.
You can get this one of two ways.
First is waiting for someone to call out they have a key on /map or /say after the Fire Elemental event at Metrica Province. Head to the barrier in the middle of Thaumanaova Reactor and wait for them to activate the panel til you can jump in. Kill the Displaced Steam Golem and you're done!
Second involves finding the key yourself, and the best way to tell you to do that would be following this page. You have to actively use your interact key, as you won't get a tooltip come up to tell you when.
After acquiring the key go you will want to get four different elements on your key, which involves you running to four different spots in Thaumanova for the associated element. Pictures below.
The final spot you will want to participate in the Fire Elemental event at Thaumanova Reactor. Get through that event and you will be able to interact with the golem that started this whole mess. Interact with him to charge your key with Fire.
After! Run to the middle of Thaumanova, interact with the control panel in front of the energy barrier then jump on in to the open pit!
Kill the Displaced Steam Golem and you're done!
When The Frozen Maw event gets started, head to the Vendrake's Homestead Waypoint in Wayfarer's Foothills. Head on up to the Heart of Corruption Point of Interest and take out the Svanir Shaman before he finishes his ritual. In larger servers it's practically impossible NOT to complete this achievement.
After the first phase of the Claw of Jormag fight, located in Frostgorge Sound to the Northwest of Earthshake Waypoint, before he gets shot out of the sky and moves to his second position you will want to move to where his icon is at on the mini-map. Standing here will get you the achievement, but you will die, so make sure you have a buddy or prepare to run from a waypoint.
Kill the Hydra Queen
The meta-event chain “The Campaign Against Taigha Covington”, located in Bloodtide Coast, is how you get this achievement.
This meta-event starts with “Defend Lionguard Lindi as she searches for buried treasure.”, which starts just north of the Laughing Gull Waypoint, and immediately followed by “Protect Bill and Hekja as they clear Risen from the area.” You'll need to complete the second meta-event about two or three times, until the NPCs leave the island.
After this the meta-event will start when Jenny and the others return to the Lionguard Galleon. You'll go through a few meta-events to take over the Keep slowly, until it finally comes to “Kill Admiral Taidha Covington.”.
It's recommended you have a full group for this, and when you are fighting Admiral Taidha you need to make sure Jenny does not die. If she does you will not receive credit for the achievement.
This one is a bit more difficult to achieve consider the sheer amount of numbers and the recent changes with the Shatterer. Get to Blazeridge Steppes, just at the Lowland Burns Waypoint, a little before the meta-event for the Shatterer starts.
You have to break the crystals that capture players, and the only advice I can give is to prepare a fast attack for the situations in which a player may get captured.
This will probably take a few tries before you finally get the achievement.
That Had to Burn
At the Tequatl Sunless World Event, which is at Sparkfly Fen near the Shattered Coast Waypoint for those of you who don't know, you will need to be part of the group that burns down Tequatl at least to 75%.
After that you need to participate in protecting the megalaser, and if you manage to achieve all this, then you will get the achievement when the laser goes off.
As of current changes this event involves a lot of coordination to get that point. Highly recommend you guest to a more popular server, or follow a coordinated guild for this effort. Also highly recommended you got on some sort of VOIP for this as well, so you can hear instructions and reasoning from whomever is leading the attack.