Mortal Strike x Beacon of Light
Fast question (wotlk): If target has Beacon of light on him and receives "indirect" healing via it, but also has mortal strike on him as well - will this healing from beacon be cut by 50% from MS? I thought yes, but I found just that this was fixed in cata and didn't have chance to test it out so far:
Cataclysm Hotfix (2010-12-14): Healing done by Beacon of Light is now properly affected by healing modifiers on targets which reduce healing done (i.e. [Mortal Strike]).