An engine will cost ya 440 pts. Thats allot at 1,5K.
Yes it will boost your magic, provide a 5+ ward save and drop a terror causer on the board, but at 1.5k your magic is a skink priest knowing lore of heavens....a.k.a. not brilliant!
The 5+ ward is really good! but is it 440 pts good?
imho you'd better go with the chief on a ancient stegadon and a spear.... (or maybe even better...with the drums...) I know, i know that means only 1d6+1 impact hits vs 2d6+1, but everybody and his grandmother will expect the spear and wil marchblock that dude from the getgo.... Knowing you can march anytime and position your steg as you chose is really potent and unpredictable for your opponent.