if you are playing end of winter like I usually do.
ah yes, it can be quite fun to play Illians on End of Winter ... however thats kind of like playing high sea level as the Lanun, and commenting on some ocean mechanic.
Frankly, on Archipelago maps, you will hardly ever have an army because of the low hammers, but so will everyone else, and you will have a massive economy, so your Tsunami wielding Eidolons, and RoF wielding Eidolons will be meeting their champions most likely. Of course, to do this you need to spend some time in AV ... and depending on how much land in the map it may be better to just build cultists, then go pure AV, and upgrade those cultists to tsunami eidolons, and bring along Mardero and some Beasts of Agares. And hopefully you will have enough left over cultists to destroy those attacking your other settlements. And if not .. ther are always ritualists, and you will probably soon have either longbows or Arquebus depending on how deep you went into which techpaths ... and city garrison archer + ritualist or cultist makes for a tough to take city while your main force is off in a huge stack of boats, crushing everyone else. Of course, if you went with the cultist -> eidolon path, most likely you can just waterwalk those Eidolons over to your enemy, with the ships as back up, and the ships can either bring Mardero along or he can sit as Defense, and if you managed to Build Rosier, he can defend your biggest or most important Island.
as for the Samhain, combining Stasis with an early Samhain can prove annoying, but ultimately in mp games it will be uneffective. If someone has Rexed and dies from it, then laugh, but for the most part I consider Samhain as a noobtrap, and I consider late game Stasis to be the most effective. Unfortunately that means they will have been able to build their army, but the idea is that you try to kill their army that turn, or what not, and they cannot build troops as you march upon them. Another good tactic is to wait until they are away from their lands.