Don't use Raging Strikes right away. Instead:

Bio II > Miasma > Bio > Swiftcast > Shadow Flare > Raging Strikes > Fester > Thunder > Bio II > Miasma > Bio > Contagion > Ruin II > Fester.

Depending on your latency, smush Spur/Rouse in there wherever you can (right at the start is fine, too). This maximizes Fester with RS.