Redox reaction; standard cell potential

lemin_rew

1. The problem statement, all variables and given/known data
Find the cell potential of the equations
Mg^+2 + 2e- --------> mg E=-2.36v
Cl2 + e- ---------> 2cl- E=+1.36v

Ans: -1.00v

3. The attempt at a solution

The answer says that it cl2 should be flipped. And cl2 is the anode
But I don't understand why. I thought the -ve value sholud be flipped,
Also why is cl2 the anode, it's very high up on the SOA chart, which is cathode whereas mg is on the bottom. Is there any way to figure it which one is cathode and anode without the chart?
Is the more negative value always going to be flipped?
Can someone explain this.?