Board Thread:Question and Answer/@comment-67.129.66.62-20161013224327/@comment-26494010-20161013230210

Look at your cards and see what you need more. Saurva is a dark elemental buffer so you need a full team of good dark cards to use her with. Letta is a snowballer that buffs all cards. With Saurva, you'll need to build a full team of good dark cards that at least include full nullers and unleashers, and if you don't have that, then Letta is the better option. However,  if you think you can get another Letta before the event ends, go for 1 Captain Saurva.