Attacking Pirate Ships
 

Can I attack pirate ships at will or will it break some quests? The pirate ships just roam the seas around the islands and don't attack me on their own. There is also a Giant Hero on the Western Isles - same question - if I kill him, will it break any quests?

No, it's safe to kill them.

The only quest you can break this way is with that pirate captain that asks you to speak to the priests.

Excellent - thanks! I have already spoken to the priest and finished that quest, so it is time for some pirate-clearing!

but you may consider not to attack pirate ships now and leave them as easy fights for the fucture (like leveling down Pain Skull's spell-I bought it in Demonis and had not much easy fights so I'm now in Haas Labirynth and got 41% of this spell to do)

This is good point, but you should always consider counter-points prior deciding:

Returing is time consuming (lower score, more your own time)

You get less XP (stronger you are, fewer xp you get as reward)

Less fun (even fighting MATCH or slightly stronger neutrals may become a routine for skilled player, so fighting WEAK and weaker would be nearly not funny at all)

If you are afraid your pains skull won't be transformed (happend to me as well) - first check if you really need the upgraded skull so much, than also consider that you may fight many gremlin battles (just use items with morale - which are actually the best artefacts) - you may collect many artefacts where even w/o morale are battles needed (like "get spell xy if you win" with 5 charges = 5 battles... etc)

I was very disappointment that they not attack you, on my first go i run away from them, try to sneak etc. but when i found that they don't act hostile i felt very sad, another fun aspect was took from me in this game.