Engineer I expect to be able to repair the castle door and other equipment. Also we know it will be able to build/summon a robot so perhaps it will be a little more offensive than the current cleric. I hope maybe they will give it an ability to toss a wrench or something like the warriors Rock Throw skill so they aren't so totally helpless against ranged/runners. I doubt they will buff Sacred Armor, it's already a strong skill as is. As for a new team skill, maybe a massive radius Dispel that also removes corpses (like pressing 'Y' to spawn stronger) to prevent spamming revive at your tower and halt any construction around your castle.