In addition to Drax, which is listed, I would also include the 12 issue Thanos series as a lead in. Especially 7-12 which was written by Giffen and introduced a few characters seen in Annihilation as well as the return of Starlord.

Guardians of the Galaxy: #14-18 (sorry, missing issue 13 so can't include it)

The Guardians teleport into the throne room on Attilan, bringing a message that war is bad, and the looming Shi'ar vs Kree war could destroy all of reality. Unfortunately the Inhumans are $$$-holes about the whole thing, and then Phyla-vel doesn't exactly help when she pulls her sword on Blackbolt and then Crystal (after Crystal tries to calm things and hear the Guardians out). The poopy is about to hit the fan when Peter breaks them apart and tries to teleport out.

Elsewhere, Warlock is trying to get Vulcan to listen to him, and it's also gone south. Seems Vulcan doesn't care, he's to damn narcisistic to worry about it. He and Warlock start to throw down, which causes the Magus to manifest himself. Warlock/Magus starts to slap the carp out of Vulcan and the Imperial Guard shows up. Out numbered and out gunned Magus/Warlock portals out. Sadly, it's not good as the IG spell caster has put a witch mark on him to track him anywhere/anywhen.

On Knowhere, Quill and team have portalled back in only to find that Phyla is totally off her rocker and has kidnapped Crystal. Quill and co start to pull Phyla off and tell Crystal everything that's about to happen if the war keeps going. That's when it goes into normal mode for the mag and Warlock, the IG, and the Inhumans all show up. All of them uber pissed off, and all of them looking for blood. The Guardians can only flee as the mother of all intergalactic throw downs start.

The Inhumans nab Crystal and portal back out while the IG stay, intending to annex Knowhere as an IG outpost. It's looking bad until Rocket, Groot, and Astrovic show up and begin beating the stuffing out of the Guard with the help of a returned Drax. The four of them are thumping the snot out of the Guard. Meanwhile Gamora and Phyla-vel have turned the tables on their pursuers and begin working their way back. Moondragon is under the mental control of Starhawk, who brings her down to her jailcell so that Moony will free her.

Warlock has figured out how to ditch the witchmark and puts it back on the IG spellcaster, causing the other Shi'ar to kill her by accident instead of Adam/Magus. Magus/Warlock and the other Guardians show up and the IG barely manages to escape them.

Just then Starhawk portals Jack Flagg, Mantis, Starlord, Bug, and Cosmo into the future. There they discover that the universe is ending. Something set off a universal fissure called the Fault which is eating all reality. The Badoon have used the last remaining Cosmic Cube to enslave all Celestial to make a giant forcefield keeping the Fault at bay for a while. The future Guardians and our Guardians team up, only to have the Badoon show up and blow up Dr. Doom's time machine before they can go back and stop the Fault. So they flee the floating base of the future Guardians (the Avenger's Mansion). and decide to make a suicide run on the Celestials to send a massive Teep message back in time to warn Adam Warlock and tell him how to stop the Fault.

This pulls the Celestials out of alignment, and they begin falling into the sun. The Guardians appear to die, but the message gets through. Adam and the other Guardians unfortunately can't stop the Fault, because at that moment Blackbolt detonates the T-bomb ripping open the Fault. The surviving Guardians portal to Attilan to talk to the Inhumans and hopefully come up with a plan to stop the Fault's spread.

Here they are attacked by a giant space Cthulu monster (or rather the whole city is). Groot and Maximus the mad come up with a plan to fight off the Cthulu monster and save the city. It appears that when Groot says "I AM GROOT!" he's actually saying all sorts of other things, that or Maximus is flarking crazy as a bag of spanners (although the art hints heavily that he's not making it up). Groot and Maximus build a reality generator that kills off the Space Cthulu's reality, reasserting our own temporarily. It's not enough though to halt the Fault's spread, and Warlock/Magus portals out with Gamora and Phyla to create a spell which will stop it (saying it will require a LOT of energy).

Meanwhile we find out the other Guardians did not die, but got flung into another time stream. In this one the Future Guardians are fighting off HG Wells inspired Martians who have overrun Earth. Starlord has arrived as an 80-90 something year old man, Cosmo is a puppy, Mantis a baby, and Jack Flagg is slipping sideways through time, phasing out of reality. Starlord of this era recieves a message from all other Starlords telling him whats happened, and what will happen. So he gets the Future Guardians to help the old Guardians break into the Avengers Mansion of this time and steal Doc Doom's Time Machine. He also reveals that apparently Jack Flagg is the key to fixing things. Apparently he's some sort of universal savior, but won't say how or for what.

Back in our time, Adam manages to weave a spell using the Universal Church of Truth's Belief Engines to generate the power. He does it by grafting an un-used timeline onto ours. Apparently one he is already from as we are about to find out. Phyla-vel stabs him through the chest just as he saves everything. Gamora attacks her thinking she's gone crazy and kills Phyla-vel. Unfortunately, Phyla was bang on target as Adam gets up revealing he's actually Magus (apparently he's been him for some time, as we kept seeing Adam/Magus flop back and forth). He's perfectly fine, and kills Gamora and then takes over as the head of the church.

At this point the other Guardians show up to find a giant icon of Magus floating in space, with the temple ships covered in his image. Uh-oh!