Well, let's start with the obvious:
/cast [target=target,help] Righteous Defense; [target=targettarget,help] Righteous Defense
Translation: If I'm targeting someone I'd want to help, cast Righteous Defense on them.
If not, then I must be targeting a bad guy. Target
their target, and cast Righteous Defense.
If you wanted BoP to act as a backup taunt, you could macro it the same way -
/cast [target=target,help] Blessing of Protection; [target=targettarget,help] Blessing of Protection
Please note: While you can't accidentally Righteous Defense yourself, you can accidentally BoP yourself if the mob re-targets you just before you hit this. This could happen if your original target hits Feign Death, Fade, Vanish, Cower, Ice Block, or uses Improved Feign Death, i.e. gets killed.
Another minor convenience I have, bound to 2:
/cast Judgement
/stopcasting
/cast Seal of Righteousness
For when you're chain-judging Righteousness - this works with a single keypress since Judgement doesn't activate the global cooldown. And since it's instantaneous, SoR should always be there for your next attack.
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Scarlet Crusade - Tanked 11/11 Kara, 2/2 GL, 1/1 ML, 6/6 ZA, 0.5/5 SSC, 1/3 TK, 1/3 MH, 2/4 BT
I'd trade any libram for a green gun of the Champion.