The thing is that by the time you've reanimated either Kelpie or Sage, you've probably used up most of the flashback cards in your graveyard that you're going to be casting that game. (Remember, there are only 6-7 manaless flashback cards in the deck, at least one of which you just used.and you're using DA to dredge first.) And while Kelpie is better as an engine, Sage just gets there with the 15-18 cards off the top from the start.
I cut Salvage, 1 return, and 1 thug for 2 more studies and one more DA. My sideboard looks like the following:
4 Leyline
4 Chain of Vapor
2 Chalice of the Void
2 Pithing Needle
2 Ray of Revelation
1 Woodfall Primus.
The reason for the split between Chalice and Needle is that I'm not sure which one is better, given that Pithing Needle answers on-the-board Crypts and shuts down other problem permanents, and Chalice gets Crypt and Explosives simultaneously, can get Extirpate, and gives me something else to combat combo besides racing/getting lucky with Therapies. My boarding plan is as follows:
vs decks with a bunch of creatures who are siding in Crypt
-1 FKZ
-1 Cephalid Sage
-1 Ichorid
-2 LED
-2 DA
-1 Careful Study
+4 Leyline of the Void
+2 Pithing Needle
+2 Chalice of the Void
vs decks with a bunch of creatures who are siding in Leyline
-1 FKZ
-1 Cephalid Sage
-1 Ichorid
-2 LED
-3 DA
-2 Careful Study
+4 Leyline of the Void
+4 Chain of Vapor
+2 Ray of Revelation
vs. non-creature decks with Crypts
-1 FKZ
-1 Sage
-2 Careful Study
(-1 LED on the play)
-1 DA(-2 on the play)
-1 Thug
+4 Chain of Vapor
+2 Pithing Needle
(+2 Chalice on the Play)
vs. non-creature decks with Leyline
-1 FKZ
-1 Sage
-2 Careful Study
-1 DA
-1 Thug
+4 Chain of Vapor
+2 Ray of Revelation
vs. Extirpates and Combo
-2 Careful Study
+2 Chalice of the Void
And the one Primus is in there to beat up on random prison, enchantress and such by killing two permanents in one turn at least. Probably you pitch a study for it.
Does that look like a good plan? I might go to 4/0 on the Chalice/Needle split, but we'll see.

