Ivs and builds for sanaki and deirdre!!

+Atk -Def is probably Sanaki's best IVs.

As for Deirdre, I guess it really depends on how you're going to use her, but I prefer +Atk.

Yeah Sanaki really wants +Atk. She'll honestly get more mileage out of the extra damage than speed, as she likely won't double much without a breaker skill anyway. My +Atk Sanaki has Axebreaker, I honestly don't remember what mine has for a bane. But -Def is probably better as keeping her hp neutral means slightly more magical bulk.
Unfortunately I can't offer any help with Deirdre as I have zero experience with her in Heroes.
Edit: checked and my Sanaki is +atk/-spd.

Deirdre for dragon killing loves attack or general use wants speed or attack, so take the attack boon. Sanaki also loves to boost her ridiculous attack stat, but could also work well with a speed boon and a build that min/maxes her speed. That decision is up to you.

As for builds, fury/iceberg to go with her base kit is good for general use, but a dragon destroyer build wants watersweep 3 and skills to min/max her atk/spd.

Sanaki is a nuclear missile with +atk. You can have her hitting for 59 base attack with just a refinement and a flier ally close by, and skills such as atk/res bond or death blow make her a player phase nightmare. With res ploy C slot and and attack seal, she can effectively have about 70 attack with all base skills considered and her target ployed.