Forum:Macro Cosmos clarification

Could somebody clarify what situations you cannot activate cards that send to the graveyard?

i understood why you could not activate charge of the light brigade, but why does lightsworn eff's still activate. arnt those costs as well(technically costs?)

Also does a card such as foolish burial activate if macro is face up? if so then what happens? and can you give me a bunch of examples where cards that send to the graveyard can activate?