gamexiao: There was a cave that I found with 7 dragon.

What is a good strategy that you can use to defeat 7 dragons with minimum losses?

HomerSimpson: Don't fight them? I'm not being sarcastic when I say that. I've noticed that there is the odd encounter here and there that seems to be unwinnable almost by design. I just let them be. There's easier pickings to be found.

yevalia: Long-time lurker here, but finally adding my 2 cents.

I usually play in semi-sandbox mode on (Colossal, 4-6 enemies) on expert and have cleared site with 7 dragons twice (and twice with 6 dragons).

Gremlion's strategy with the level 30 Beserker works with godly equipment. I had the following:
1 - Hammer of Creator (no stamina loss)
2 - 2 vampiric rings (that's 40% vampirism)
3 - Either Floating boots (cannot remember name), or Belt of Levitation, or that 'Flying chainmail' (so you can 'float' into the middle of a pack of dragons and round-attack for max. vampirism).
4 - I also had 2 rings that extended duration of spells by 1 turn each (since stamina isn't an issue), effectively making vampirism spell last for 5 turns instead of 3.

If you have the above, and a bunch of dragon-food / cannon-fodder for the rest the slots:

Turn 1 - cast vampirism (get 80-90% vampirism for 5 turns - sweet!) - initial turns are when dragons hit hardest and you'll need the 90% bloodsucking to stay alive.
Turn 2 + - round attack, round attack, round attack, round attack...

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I've also done this twice with a level 30 Archmage and his level 30 pet hydra with nice medals. The mage will need about 65+hp from various equipment (Archmage robe is best) for him not to die. Managed to find 2 spell-scrolls of "Invulnerability" (I usually take the school that has 'Mass Suicide'). So, take the pet hydra and fill out the remaining army slots with more dragon-food:

Turn 1 - cast Invulnerability on mage and hydra
Turn 2 - cast vampirism and haste (optional) / astral on hydra
Turn 3+ - (dragons start to attack mage standing in corner)... hydra does all the attacking. So it goes something like this - hydra attack, astral, astral... astral, astral... Make sure the hydra is near the mage as the mage is the dragon-magnet and hydras are slow.

The archmage still takes damage from dragons even with Invulnerability, but he'll survive the combat with about 10-25HP by the end of the encounter. Option is to cast 'Phantom Form' on mage but it isn't necessary. The hydra meanwhile with Invulnerability and Vampirism will come out of the battle healthier than ever.