Since we're talking initiative, we use a more controllable system than RAW.
You can add up to 20 pts to your init, but this is a penalty to the first declared action.
Or
You may subtract up to 20 pts from your first declared action and add this to your init.
(So we have one guy who records init and the +/- Init/OB for the party. Then I start counting down inits from ~35. They don't know when the opposition is going to act, until it happens.)
This is kinda, sorta similar to Phases, but the player decides the amount; up to 20.
The Magician should have a chance, not totally dice dependent, to lunge at a Fighter and hit first with a sloppy attack.
Do you want to act fast and sloppy or slow and precise or anywhere in between?
This and %Activity rule the day for us.
It's not perfect, but it works for now and they like it.
And yes, if you take a bonus on init because you're rushing a spell, the penalty can be very bad on the spell fumble table.