Combat Sense (the Spell, not the Adept power) increases DR for net hits-value and costs 3 drain. Plus bonus dice for surprise tests.
Amor (the Spell, not the gear) does the same without bonus dice and costs 4 drain.
Any explanations for that? Maybe Combat Sense should increase the defense test (reaction+intuition) and Amor the DR, and the drain should be reworked.
Anyhow, a spell that has to be sustained should not affect surprise tests. Thats like telling my kids: "If there is a sudden bang, cover your ears".