Get rid of heroes and keep your building levels low.
That's the only way I know of.
Eating your heroes is the only way to lose might.
Seems some ppl have smurf accounts and they concentrate on getting the best possible heroes and leveling them up while keeping their base builds to a minimum.
Don't do it! Deflating might is the WORST thing you can do for yourself in this game. The ONLY thing it does is make raiding slightly easier. On the other hand inflating might gives better daily rewards, quest rewards, more quests to complete, arena bonuses, and makes hero expedition a LOT easier and increases the rewards for hero expedition. For example, I finish all 10 hero expeditions and get max reward probably 80-90% of the time. At 70,000 might that's around 17k honor badges and 800 merits EVERY DAY, that's more honor badges than I get from the daily tier III guild boss fight. It only took me about 6 months to get that much might so starting farming your might now! Once you get around 25-30k might raiding gets much easier (especially once you get snowstorm) and people have so much gold and mana that they don't know what to do with it so filling your vaults is a piece of cake. It is not uncommon for me to get over 1 mil gold and mana in a single raid. I know it's rough early on but you're just going to have to power through it until you get a bit bigger then you're home free. My suggestion would be to get the maximum number of hero slots in your altar (70 is max) ASAP. I like to keep one of each ordinary hero around but consume all the rest. You know all those elites you have been eating??? STOP IT! Keep them around and level them up to 40, or even 20 (if you're having trouble farming honor badges). It only costs 1k honor badges and 7.8k exp (8 green books) to level a her to 40 and it gives 140 might + whatever you get from the talent level. Keep doing that until you have 67/70 slots (just so you have room for rolling gems and consuming slimes) filled in your altar. Keep them there until you get your next legend hero then consume 1 whichever ones have the lowest talent level (talent is worth 20 might/talent level). Level your legend up to 40 or 60 and so on. Always have your builders at work, research spells constantly and train troops. Remember, more might = more rewards which makes getting more might even easier. By all means you should concentrate on the heroes you use the most but the days of having 6-8 highly trained heroes and a bunch of lvl 1 buildings are over. Inflate might as much as you can, anyone who tells you otherwise is an idiot. Between boss fight, hero expedition and quest rewards, I get about 40,000 honor badges daily (more on torch days). Between quests, storm mesa 4, dungeons and here be monsters I get 1,500 shards a day (more on torch days). Again, I have been playing for only about 6 months so I must be doing something right... Best of luck to ya.
Are u sure hero expedition become easier with higher might. Becoz I had upgraded my might from 8k to 11 k by upgrading my ordinary and elites to lvl 40 and 60 respectively just to unlock the lost realm feature..... but expeditions became really difficult for me had to face heroes lvl 100+ wid my legends capped @ 80.....
High might definetely helps with getting better in this game as there are so many rewards related to your might... A higher might brings better rewards. But you should concentrate on your main heroes. Upgrading ordinary heroes will give you a boost in might but will not help you to defeat other players. So try to improve your might by upgrading your main heroes, buildings, magic, troops, and so on.
In midrange might it seems that high might is a burden as the opponents are getting more challenging. Raiding becomes harder and expeditions are a mess. But with higher might you will get better nobility titles. As Grand DUke (58000 might) you can send 10 heroes into expeditions instead of 6 for the first titles. According to the "Nobility" page in this wiki it starts with about 19000 might that you can use 7 heros and so on. Furthermore there is an might level at which all players maxed out their walls and have to wait for their builders to finish the buildings. So they don't have anything to spend their gold on which means the raids are getting even easier with high might than with low might. :)
Now with all the sweeping thingy, I created a Guild with my 3 alt. and my main account, and I just inflated my might on the three of them to get 10k, filling the altar with angels, inscribe to max their heroes and consume the angels to deflate again.
Now I can farm G on the three of them (which means 320 *3 shards per day) so i can challenge boss 3 in my main account for free whenever i want, while I beast the 3 smurf bases with absurdly easy raids,and when I believe they are ready to go further in HBM i will inflate them again and repeat the process, if the accounts natural might doesn't reach 10k.
So, it really depends how you want to play, you can manipulate might as you wish, at the cost of spending some shards/time.
You have in this post most of the strategies to inflate/deflate might and their reasons, so just choose whichever fits you