Route up to the barrier support
Posted December 8th 2007
As you head along the path to the Citadel from rally point bravo, you approach the back of the third tower. There's a place along the upper path where the cliff slope is shallow enough to let you head up in a vehicle or on foot, then curve around to get onto the massive curving support for the now deactivated barrier. You can then do some novel stuff!
Attacking path enemies
If you've got up there before all the enemies along the path have been killed, you can find a few novel vantage points from which to attack them. In particular you can get above the Wraith and the nearby hovering platform. I lobbed a firebomb down onto one unsuspecting platform Brute and tagged the other with a spike grenade. Ah, good times…
Triggering the Scarab battle from novel places
You can use the route to get onto snowy ground from where you can trigger the Scarabs, giving you a novel starting position for the battle. To trigger them, you first you need to have gone along the usual path far enough to trigger the arrival of the Hornets. You should hear "Hornets inbound!" just past the Wraith. After that, backtrack and get onto the barrier support, then head along to the second tower. As you near it, a Pelican materializes before your very eyes - suggesting that you really weren't supposed to be up here - and you get a checkpoint. Clamber over the second tower. You can now trigger the Scarabs by approaching the snowy or icy cliff edge at certain locations ahead. I'll mention two of special interest and leave you to explore for others.
If you go left after the tower, you'll reach a snowy tip that forms a nice vantage point over the battle area. Go to the very edge of the tip to trigger the Scarabs. When plasma flies up at you, the tip gives great cover and you can stand back and admire the plasma shooting up over the edge. I also had good fun here trying to grenade the Brutes on the first Scarab; especially with firebombs!
Beneath the first tower (the furthest one around) is a deep icy gully you can get down into. When you trigger the Scarabs near the end, you've got an immediate shot at the rear of the first. You can take the back straight off with a Spartan laser, and you may be able to finish the job a few seconds later.
Exploration
If it's just exploration you want to do, you can get all the way along the barrier support and clamber around on parts of the towers. You can go beyond the first tower, right around until you're near the Citadel. You'll see one or two Banshees flying around lazily there - usually over the reddish void - waiting for the Scarab battle to kick off. You can destroy them in advance if you want (Spartan laser or beam rifle). You can also get onto high snowy past the other end of the support, i.e. beyond the third tower.
Further remarks
From the barrier support, there are a few places you can get off and go down the cliffside to rejoin the path below. You don't have to use the route you took to get up there.
Suppose you're up on the support before triggering the Hornets. If you go along to the deep gully beneath the first tower (the one furthest away), it looks like you're going to be able to get down into the battle area. However, you'll instantly die for no apparent reason. There seems to be some sort of death zone over the battle area, and I think it only gets removed after you've had the Pelican checkpoint (the one that accompanies the arrival of a Pelican) - which you can't get until you've triggered the Hornets.
If you try to drive up the route to the support after the Scarabs have been triggered, you'll get stopped by an invisible ceiling that I believe the game only added when the Scarabs were triggered (see Citadel Hornet trick for more info). But it's only a barrier to vehicles; you can pass through on foot.