There are many situations in which a mage would cast a spell in two directions at once, splitting her dicepool, eg the BBB example of using Levitate on multiple people all at once.
Got any combinations of two different spells that would fit a certain situation?
My starting example is using Phantasm and Invisibility so that just as you go invisible, you simultaneously create a decoy phantasm of yourself. You run away, while the phantasm stays there (or goes a different direction), and your opponents attack the phantasm, unless they get a good enough perception roll to spot the illusion. Bait and switch!
I'm writing a PC with the Trickster mentor and Spellcasting specialized in Illusions, so his dice pool for Illusions is large enough to split and still get decent results. Combos are extra plausible within a specialization of Spellcasting, preferably one that stacks with a mentor bonus.
If both spells are sustained, then further actions are at -4 DP; in the above example, running away should involve no actions that require checks. The Invis/Phantasm combo could be bad if your escape route requires Climbing or Gymnastics.