how you beat the octocupus?

[Gatts]

10th level is not that bad - still you may consider to fight some more fights in the pirate land (of course if you didn't already )

Apart of no retaliation units (like vamps/royal snakes) also use bandits : they can use the bludgeon ob-one-hex attack ...

always stock your units so you will have one "tank" unit - use this unit to provoke the octubus to use normal hand-to-hand attack instead of summoning devilfish - it may become nasty to have full battlefield of devilfish.

If you really have spells like phantom/ necro call/ demon portal/ or units that can summon thorns - use these units as your "tank" units for the provokative manouver - unless you already installed "improve AI" mod where the AI does more often ignore such "fake" units and attack your core units instead