You can control the number of creatures in order's graveyards to ensure that your disposable army gets smashed, so exile stuff from graveyards with things like Bojuka Bog
Purple - DON!!, on DON!!, on DON
Cards like Darksteel Reactor, Helix Pinnacle, or Azor's Elocutors make for useful single-card win conditions
If a samurai or warrior attacks alone with Raiyuu out, that creature is untapped and players can get a second combat phase
Tainted Indulgence is actually pretty close to Chart a Course in power level on balance, but Chart a Course is great, and I rarely exclude it from my Cubes
A card that's been foretold can technically also be cast for free, like Scorn Effigy, but most of the time the foretold cost is greater than 0 , sometimes by a lot