ToL, per se, is not that bad. The problem is that if you compare it with Wiz Tower, a 'masterpiece' that helps wizard books a lot.
WZ costs 2 mana less that ToL
WZ channels.
WZ has the flexibility to change attack every round for free.
Ok, ToL has "1 mana each die" and it's not ugly (check hurl boulder...cost 8, you roll 7), but ha another restriction, due to the number of temples already in play (rarely more than 3...).
My opinion is: not that bad, extra action during round, tempo advantage, but... underpowered if you compare it with other similar conjurations.
I play in my Priestess book, btw!
CYA
G.