Blood Bowl

Firstly, play your campaign in real time mode, on easy difficulty, mostly you can kick the ball and run straight through the defence and score, and then just beat up the other team by placing all of your players around the ball when you have a safe lead as the clock will tick down faster (ie. no cinematics etc because your just bashing the opposition).
I used an orc team, their Blitzer's are pretty good runners and the black orcs teamed with a troll are an amazing force of strength to hold off the opposition. Throwers are useless to begin with but after a few touchdowns and upgrading they are awesome at passing. Also, pressing B to enter concentration mode, then hitting Y+X will throw the ball into a random space on the field that one of your players does not have to be in, you can then run your player to where the ball is, this is an easy way of getting touchdowns also. Just to help.

There are around 14 tournaments bar the middle one, dont think you have to do every tournament, you dont just select the tournaments with the highest prestige and go for the prize.

You need a total of 320 Prestige points to unlock 'Blood Bowl' which is the centre event, thus unlocking the achievement.

You do gain prestige by finishing among the top 2, but you'll minimise playtime by a lot if you finish 1st every tournament.

Here's a brief description of what to expect with this achievement:
Each match is 8 minutes long (to my knowledge you cant shorten this).
There are an average of 5 matches per tournament.
Tournaments are split into two groups:
Some tournaments have two groups in them, and you have to finished amongst the top two in your group to enter the playoffs, and then beat your opposition in the playoffs to win the cup.
The other time of tournament is just playoff, win every match (There wont be many) and the cup/prestige points will be yours.
..You can see which type of tournament your in by pressing "Results" and if it says Group 1 & Group 2, your in a group tournament, if it says Playoffs, well; you get it by now. ;D

You can afford to sometimes skip games in the tournaments with "Group 1 & Group 2"; you need to finish among the top two of your group, to enter the playoffs, but if your 6 points ahead of the team ranked second then you can afford to skip a game or two (The only way i know of skipping a game is to enter the game and then press start and abandon the match).

I hope this helps and if you think this is a bad solution, please message me why and if you need help you can message me ingame!

God bless.

This pops after you unlock the Blood Bowl event at the centre of the map in campaign mode.

You'll need 320 prestige points to unlock the event which is a whole heap of grinding through the other events.

I used a Lizardman team as they have a strong defensive line and fast runners. Passing/catching is not this team's strong point, so you'll need to run the ball, but once you've got a few sprint and sure foot upgrades on the runners and all your linemen have block and dodge, you shouldn't have any trouble with the other teams.

Pick events that have good prestige rewards for the winner and just keep grinding away.