Is it worth it to get death all the way up to feint, ice to tower shield, and life to satyr?
It all totally depends on how you want to play the game. Those are very popular strategies but are also wasteful of training points because you have to wade through the bad to get to the good. You'll spend points on spells you will NEVER use to get to the spells that you will use. I know people who have used one or all of these strategies and have been very successful. I've never used any of these strategies and have also been very successful. So it's up to you. You can try one of them out and if you change your mind you can watch for the training point buy-back that happens every once in a while if you want to try a different approach.
For me ice to tower and life to satyr are both a waste of points. I rarely ever use shields (maybe I should... but meh). I pretty much just buff and take the hits and defeat the enemy as quickly as possible. Shields just waste time. And as far as satyr goes? The only wizard of mine who has trained any life spells is my life wizard. I don't have a life mastery amulet, nor would I even care to use one given the stats I can get from other amulets that I'd be missing out on with a mastery, and four (probably power) pips is too much to spend on an off school heal imo.
As far as death to feint goes? It's totally worth it imo, Although seven points is kind of a lot to spend to get to that one spell, and you could easily just use treasure feints which only put a 20% trap on you. BUT of course there is feint stacking and once you get potent trap, that 80% trap is quite nice.
For me the must haves are death to feint, spirit or elemental (depending on school) traps and blades from balance, the sun damage enchantments, and your level 84? aura from star.
This is just for the way I like to play in pve only.
Feint: Highly Recommended (7 Points) Tower: Highly Recommended (5 Points) Satyr: Moderately Recommended (7 Points) I personally prefer to stick to TC, but that's up to you. Other recommended spells include Colossal (5 Points), Your School Aura in Azteca (1), Stun Block (1), Elemental or Spirit Blade (or both, 1 each)
If you're not sure if you want to train a spell, but you want to use it, just know there is a Treasure Card version of basically every spell.