I liked Illuminate the best in H1 but if they don't release the Tendril Bug for H2, then I think H2 Bugs will trump Illuminate H2. Bugs in H2 just hit the right spot. Tendril Bug in H1 is the bane of poor random teams and a source of grief. Officially known as the "Impaler" bug - area denial. Mostly a balancing issue mind you so assuming they don't tame him, although they should. Simple fix: do not make him a bullet/rocket sponge when exposed in a burrowing state. Make the bug a 3 railgun shot kill to weakpoint or 2 disposable rocket kill to weakpoint when in burrowing state. To compensate, make him relocate after getting two direct hits, as opposed to tanking a bunch - this way simply emptying mags from firearms on weakpoint won't work. Obviously an insta kill is possible if a good team cooedinates their support weapon shots in unison.
Bosses are bosses. You're gonna get whacked and wiped if you don't go in with the appropriate gear. Arrowhead could spice it up Destiny style and make it a Raid, as opposed to an unlockable direct encounter.