ב"ה
Now that there are sirens, the single non-thoughtspore creature that many forcemasters bring better be psychic immune (so skeleton knight or zombie brute or a devouring jelly). Thoughtspores became more usefull with that mind's eye.
Solo forcemasters now have lullaby in school and that hydro -2 armor so they become a little more resistant to surging wave (and tsunami), which benefit them almost as mush as arcane ward when it was released in academy core set. On the other hand, siren is a really tough opponent for a solo forcemaster, even with that hydro -2 armor. I mean, that shallow sea really hurts your ability to melee, and it both make your attacks weaker and make their attacks stronger (not to mention that it can be combined with divine protection to remove 2 dice from each attack). And of course you have against the siren the same problems you had against water wizard when they were legal (have too many dissolves and can cast dissolve from familiar, and have those irritating unavoidable water spells).