What's the most effective way to cool down a MBP 13
That’s completely normal operating temperature for graphics intensive processes on your machine. The System Management Controller gauges your machine’s temperatures and automatically adjusts the fans accordingly. Furthermore, the SMC will automatically shut your machine down if overheating occurs.

Third party tools (IE, smcFanControl) used to measure temperature and provide users with the ability to manually adjust fan settings is not recommended at all by Apple. Here’s an excerpt from Apple Support on Macbook Operating Temperature:


  While there are third-party utilities that measure the temperature of a notebook computer, it is important to understand that these utilities are not measuring the external case temperature. The actual case temperature is much lower. Never use third-party applications to diagnose possible hardware issues. 


The most important thing to do is ensure the back vent isn’t blocked in anyway to ensure adequate heat dissipation. Additionally, keeping your laptop on a hard surface actually helps ensure proper temperature control. 

If you still feel uncomfortable, there’s a multitude of laptop cooling stations available out there which will safely help cool the machine during intensive use.