A place for Eldrad's sprue and Cheap Harlequins

So as is typical, Space Marines wipe the floor with Harlequins and in their fanaticism ignore everything else to screw everyone over and aid the great enemy.

why someone would kick away the enemy that just put a grenade in their mouth, wouldn't you want to keep them close so that they get caught in the explosion?

Of course while the great space marine is capable of figuring things out because he is so great and all that the ancient Eldrad is to ignorant to plan for everything that he saw as a possibility and didn't take measures against it so that he would fail. After all we need to make sure that the Eldar fail against the Deathwatch and that their sacrifices aren't really worth the cost while the Empire is pretty much unaffected by this whole thing. Now we have a couple craftworlds who will probably be screwed over in the next mini-campaign box when some enemy takes advantage of their brief power failures and depleted, maybe even absent forces.

it doesn't say that he kicked him away then attempted to extract the grenade, it just stops with the grenade being forced into his mouth and the kick. It is in his ruined mouth so the assumption is that it went off and he didn't do more then kick him away before it happened. If I know I don't have time to get it out I would grab him so I don't die alone not attempt to knock him clear. Of course the writer makes sure that he describes in detail the fate of the Eldar the space marines are fighting but nope, grenade in the mouth, kick the Death Jester then move to something else without describing what happened next.

The Death Jester forced the grenade into the Space Marine's mouth, and the space marine kicked the Death Jester away from him. So his action would have helped to protect the Death Jester.

First of all the battle is told solely from the perspective of the Space Marines with the only exception being snippets of how Eldrad is performing the ritual and the prologue where he sets the plan into motion.

But okay, it is somewhat bearable. The booklet contains only eight pages that depict the battle and whoever wrote this STILL managed to get some plotholes in there!

1.) Artemis just knows that the Eldar are on the moon that has been deserted for a long time. Instead of fighting on the planet where the Eldar are actually doing damage he just decides to fly to the moon ON A WHIM. It is never explicitly stated how he knows that Eldrad is up there on that (from Artemis' perspective) unimportant, deserted chunk of rock. He just feels it. It could be so simple! Just say shoehorn something in like the arrival of the Harlequins activating an old alarm system in one of the leftover factories which makes Artemis notice their presence on the moon.

2.) Not only did Eldrad indeed foresee that possible future of the Deathwatch joining the party - he just IGNORES it. "I'll do a ritual that could see the demise of my whole race brought a lot closer if it fails - better ignore that unlikely possibility of the humans intervening" - Eldrad 40K
Eldrad foresees things - that's his whole deal! He is the best fortuneteller in the damn universe and this story makes him look like an incredibly ill-prepared noob!

3.) The Death Watch land with two ships on the moon but still take out the whole Masque, even though Eldrad not only feels them approaching (giving the Clowns time to react and prepare) but also with almost 0 losses. Artemis even PUNCHES the rider of a jetbike out of his bike and the Dreadnaught can still shoot his weapon even though the Clowns cut off the ammosupplier. The 'Naught is a MACHINE. Him having fought the Eldar before and having knowledge of how to kill them will not magically repair his weapon. That's like the pilot of a Rhino having experience with landmines, which suddenly enables his vehicle to keep on moving even after driving over a landmine.

4.) I was waiting the whole time for Eldrad to unleash his psychic badassery. He could have toasted the landingzone of the Marines with psychic deathrays the moment they set foot on the moon. But nope, better stand back the whole battle and prepare the ritual. Why? Why not kill the Marines and THEN tend to the ritual? There isn't something like a clutch timewindow in which the ritual has to be performed.

Moving away from the story I'll look at the missions. Even THOSE are in the Marines' favour!

Mission 1 they get points for killing our units while we only get points by holding the markers. They also score 3 points for killing Eldrad but we do not get 3 points for killing Artemis. We have to set up normally and the Marines can move their units onto the board over ANY edge. So if you were planning on hiding behind LOS blocking terrain good luck with that against an army that can come in from wherever they want.

Mission 2 and 3 are alright but in Mission 3 Artemis gets Ramapge whilst Eldrad gets nothing.

So, in the end the Space Marines win without taking any significant losses (at least the battle reads like the Clowns kill only a handful of Marines), which means that many Craftworlds are drivting through the webway/realspace without power and it is unclear which consequences the failed ritual has on the souls that Eldrad used to power it.