Choose one —
• Sacrifice any number of creatures. You gain 3 life for each sacrificed creature.
• Pay X life, then look at the top X cards of your library. Put one of those cards into your hand and exile the rest.
Entwine {B} (Choose both if you pay the entwine cost.)
Assuming the entwine cost has been paid, the effect is (1) sacrifice any number of creatures, (2) gain 3 life for each sacrificed creature, (3) choose X, (4) pay X life, and (5) look at the top X cards of your library, put one into your hand, and exile the rest.
Everything other than the mode/entwine choice (and paying the {1}{B}, of course) is done on resolution.