Class 4.6 Demolition Dash
Class 1.0 Rush
Class 5.0 Destruction Magic
Class 7.0 Magic Control
Class 5.1 Magic Bullet
Class 5.0 Shot
Class 2.0 Curse Magic
Class 5.0 Gun Knowledge
Class 7.0 Magic Control
Primary Stat - Magic (Focus on DD first)
Secondary Stat - Speed (For boosting MB damage)
Can be completed at level 80 (A first for me to make a build that isn't completed at 90!)
This build is one that focuses on flexibility as its main point of power. It obviously cannot focus on both DD and MB damage, so it won't be as strong as any pure DD or MB.
If I were to play this build, and I intend to, I would be using DD primarily as a form of damaging things, and using MB to pick off faraway targets and deal damage using otherwise unavailable affinities to the DD. THIS BUILD WILL LIKELY JUST SELF-DESTRUCT ITSELF IN PVP DUE TO ITS WORTHLESSNESS THERE. As you may have guessed, I would not recommend its use in PVP.
The perks of this build include obtaining all skills from both the Demolition Dash and Magic Bullet chains, as well as a maxed out Magic Control Expertise for use of all damage-boosting toggles, since they would apply to both DD and MB.
---AFTERTHOUGHT---
If you add 1 class of Bless to this build, you'll gain access to COTW. Epic.