Pinball FX2

First , to start a mission, you need to hit the ball into the URU hole 3 times to drop the barrier, then hit it into the yellow sink hole behind that.
To make this easier, you need to master the Lightning Strike combo.
Look at the table by holding X. See the upper right mini ramp behind the upper right flipper? That's the YMIR ramp.( 1 letter of YMIR lights up every time you hit the ball through it) If you hit the ball there using the upper left flipper and then immediately pull back on the launch Stick ( right Stick) or the a button it will push the ball right through the destroyer ramp ( lights up 1 letter of ARMOR every time you hit it up that ramp)
These 2 ramps are the hardest to hit and this makes it a little easier. Now to make it even easier to hit, hit the ball up the Loki Ramp ( the green one, lights up 1 letter of Serpent every time you hit it up there) Once the ball goes up the ramp and starts down, pull back on the launch stick , the right stick or the button . This will drop the ball just above the upper left flipper making hitting the YMIR and Destroyer much easier.
Practice it til you are good and you will have a much easier time completing these missions.
I've also posted a video at the bottom for completing this combo. This guy plays on PS3 so when it says press X in the video, either pull back on the launch stick or hit instead
Now on to the missions.

Brothers-

This mission requires you to defeat Loki. Hitting the yellow ramps will take 1 point of health from Loki, hitting the blue ramps takes 1 point of health from Thor. Each has 7 hit points. However I usually hit Loki's green ramp then hit the Lightning strike combo. This will take off 1 point from Thor, but take 2 points from Loki. Since this is the easiest ramp for me to hit, that's what I always do. Simply hit any yellow ramp a total of 7 times will accomplish this.

The Destroyer

If you look at the dot matrix, you'll see that the counter is counting up from 50%. You want to make it go down to 0. Hitting either of the yellow ramps on the left will lower the percentage about 10%. Hitting the bumpers above the volcano will lower it about 2% per bumper hit. Depending on which flipper the ball is on determines what you should shoot for. I usually try getting it to the left bumper and hitting it around the far right ramp into the bumpers. Hopefully it will bounce off these lots of times in a quick succession and end the mission quick. Although it might just hit them few times and bounce out. Keep hitting either the yellow ramps or the bumpers to complete the mission.

Ymir Attacks.

You must hit the lit lanes to attack Ymir. Unfortunately many times you don't have a good shot at them and for this mission you can't hit Lokis ramp to do the lightning Strike combo so I'd suggest almost any time you have the ball on the left side, keep hitting Lokis ramp because this will bring Thors health up a little. There are only 2 lanes lit at any time and they change every 8 seconds or so if you don't have a good shot at one, wait til the lanes change and be mindful of Thors health. If it's getting low, hit Lokis ramp a few times to bring it up.

The Destroyer in Asgard

Here's where the Lightning Strike Combo really comes in handy. You must hit 3 ramps in order to hit the Destroyer and you have 60 seconds to hit all 3. If not, Thor looses 1 point of health. The 3 ramps are the destroyer ramp, Ymirs mini ramp, and the little U-ramp to the left. You must hit them in order. If you hit the URU hole, this will drop the ball right above the upper right flipper for a shot at the destroyer ramp. I only seem to hit this about 25% of the time. However if I hit the Loki ramp I can easily do a lightning strike combo and hit it easy. Then do the combo again to hit the Ymir ramp. In less than 10 seconds I have 2 of the 3 ramps usually. Then I just need to hit the remaining ramp before the 60 seconds is up.
If you miss the Loki ramp or the combo after the first destroyer ramp shot, if you hit the URU hole, this will deposit the ball right above the top left flipper for an easy shot at the Ymir ramp.
You need to hit these 3 ramps 3 times to complete this mission.

Ymir Rages Again

You need to hit 2 ramps 3 times to complete this mission. However there is ice blocking the ramps. So you must first hit the ball into either holes under the volcano to light the ball on fire. Then hit the ice twice each before sending the ball through the ramps. You must do this 3 times to complete the mission. This is the hardest mission at least for me because many times hitting the ball into the ice sometimes results in the ball bouncing into either out lanes or right down the middle.
I also posted a video of someone on PS3 doing all the missions if you need help.
If you want more info about this table visit the guide on the Zen Studios forums here:
http://marvelpinball.com/table_guides/Thor%20Table%20Gu....pdf

Good luck.

For this achievement you must defeat all Asgard missions. The missions are Brothers Duel, The Destroyer, Ymir's Attack, The Destroyer in Asgard, and Ymir Rages Again.
To start a mission, you must spell "URU" by hitting the ball three times into the middle hole. Once that's done the gate will drop and open up the rainbow bridge hole. Shoot the rainbow bridge hole to start a mission.

Brothers Duel- The blue flashing lanes and ramps represent Thor and the yellow flashing lanes represent Loki. Shoot any of the blue lanes or ramps to hit Loki. Do this seven times to complete the mission.

The Destroyer- You must increase Thor's power by hitting the bumpers multiple times, shooting the flashing yellow ramp or left loop to take down the Destroyer. If no shots are made, the Destroyer's power will regenerate. Drop the Destroyer's power down to zero to complete the mission.

Ymir's Attack- Shoot the flashing lanes and ramps to hit Ymir. There are two flashing lanes that will alternate every eight seconds. Meanwhile, Ymir is draining Thor's health. To increase Thor's health shoot the right green ramp. Hit Ymir seven times to complete the mission.

The Destroyer in Asgard- To score a hit on the Destroyer you must make three different shots for one hit. The center hole will help set up the shots you need. First shot will be the loop in the center of table,( under the middle hole). Next shot is the right loop,( under top right flipper). The last shot is the u-ramp,( below right volcano). Repeat this three times to complete the mission.

Ymir Rages Again- Ymir has two flashing lanes blocked by ice. The top middle lane and the green right lane. To break the barriers you must ignite the ball by shooting it into one of the holes under the volcanoes. Next, hit each barrier twice while the ball is on fire to open up the lane. Then shoot the ball into the open lane. Repeat this three times to complete the mission. Hope this helps.