Mythtacular is an obstacle course forged on Sandbox for Halo 3's default Slayer gametype. Scroll down to check it out!

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The Rules, if you’re a hardcore by-the-rules kinda person:
0. Use Halo 3’s default Slayer gametype
1. No weapons, no grenades—only melee
2. No assistance from other players
3. Navigate obstacles, in order, as design dictates

The spawn area; continue straight ahead to challenge the obstacle course. On the right are checkpoint teleporters.
These teleporters are already unlocked—I’m not silly enough to expect people to complete this map in one sitting. There is also a transport hornet under the spawn area for when you’re in a hurry to get to a specific obstacle.

SECTION I:

Avoid the teleporters while you slide down

Careful control of the throttle is key—don’t rush
TIP: Pump the throttle, especially when crossing seams. Otherwise your mongoose may stall

This one is …involved. You must built momentum using a pair of teleporters in order to pass through a hoop in the sky. That hoop contains a radar jammer, which you must jump off of to reach a second pair of teleporters and repeat the process.

Roll the golf ball up the ramp--as it rolls down, it will block the receiver nodes (very briefly!) and permit you to pass through the sender nodes.

As you come around the back of the fourth obstacle, you’ll find the first checkpoint and conclude section I

SECTION II:

Another radar jammer-assisted jump will bring you to the fifth obstacle… you must make a bridge from deployable covers! You have to be quick to both build the bridge and make it across before they time out.

Radar jammers to the rescue again

This time, you must build a staircase from deployable covers

My favorite obstacle; in the enclosure above are two grav lifts, which you must deploy into the mancannon structures below. Exiting the enclosure (which requires a flare-assisted jump, preventing you from bringing a grav lift outside), you will find those grav lifts you deployed soaring across the gap between the platforms you must reach. Time your jump carefully to coincide with the grav lifts and you’ll just make it across.
TIP: Take care to aim when deploying the grav lifts--the mancannon alignment doesn't work for sloppy throws

You should still have a flare, which will get you across this gap and conclude this section of the obstacle course!

SECTION III:

Time your leap so as to jump off of the golf ball in order to make it across. Parts of this obstacle are submerged in the killzone—don’t try to cheat or you’ll die

This spastic, erratically ricocheting golf ball is your stepping stone to the ledge above

Stand on top of the golf ball and proceed down this platform. Enjoy the tilted parts! :) Parts of this obstacle are submerged in the killzone—don’t try to cheat or you’ll die

Take it slow on this twisted balance beam

These jumps are simple but have a very unforgiving margin for error

These jumps are both a reprieve and a gift, courtesy of the OLN. Don’t rush and you’ll make it across this section easily.

Climb this staircase to conclude this section

SECTION IV: The final obstacle!
This is it—the culmination of Mythtacular. I saved the best challenge for last!

Standing atop a golf ball, roll off the edge of the cliff. You just might reach the bottom, where you’ll have to cross narrow supports while remaining on top of the golf ball. Finally, if you make it across, you’ll have to climb straight up using only tiny metal poles. Parts of this obstacle are submerged in the killzone—don’t try to cheat or you’ll die.

(just in case you're worried, the wall is "magnetized" so your descent is slow and controlled. You might even have to jump/melee the ball to detach from the wall, depending on just how slow you descended)

Win!

If you complete this final obstacle, you will have completed Mythtacular!