I'm going to be stacking test/deca/d-bol/epistane for my next bulker with roughly a 50/50 mix of the d-bol/epi, i'm thinking 20mg of each, and the epi will help with estrogenic sides and complement the androgenic d-bol. Personally if your just stacking an oral with test E then i'd say something that is heavily anabolic and not too androgenic, so superdrol, turinabol, anavar, winstrol, epistane, to help solidify and add more permanence to your gains. Or at the very least end with a pure anabolic.
Things to keep inmind:
D-bol is notorious for causing water retention so bad you can get a "moon face"
D-bol aromatizes to a high powered estrogen and can very easily cause gyno
D-bol reduces cardiovasular endurance
D-bol boosts igf'1 levels significantly
D-bol in doses as low as 10mg/day boosts hormone levels over 3 times normal
D-bol is very effective at lowering SHBG