3, 1, 2, 1, 3 or 3, 1, 1, 1, 3 is what you want to use (some situations may be better for you to have the CC sanctum). The last talent at 3 allows you to spam more dragon helixes because it only consumes 1 spectral orb outside of SB instead of 3. This is why many warlocks no longer use TD when there are other SBs in party because it is a big dps loss for shadow warlock to not spec for talent 3. For your new rotation you could do Summon Thrall (tab) > C > SB (tab) > V > 2 > 3 > spam 4 and RMB. Since thrall takes a second to actually use SB after pressing tab, you'll be able to get the start of your rotation out before you receive SB.