[youtube]y6-uVDJ_CIc[/youtube]
I think I'm starting to see what the battle system is like. Though this is a guess I think the turn-based battle system works like this:
There's these turn slots (I think there's 8 in the video I have to recheck) and the player/master tells what the servant does in those turns (like setting up a strategy like in SRPG with combos) like Attack, Defend, Special Attack,etc... Also I think it may have a rock-paper-scissor method of battle as well depending on what actions the player tells the servant to do which resulted in the "Evade" action in the first trailer.
I'm not sure but it seems like that or close to it and that's pretty interesting. A different take at turn-based RPGs as it reminds me of Persona a bit and I love those RPGs. I can't wait until this game comes out, I like to try it.