(b) list 3-5 spells, maybe 2 at will, 2 3/day ones and maybe 1 x 1/day one.
at will - Ray of Frost
3/day - Hunter's Mark, Pass without trace
(hard to think...more later)
I like the
hunter's mark.
Not sure about
pass without trace, gnolls being destructive creatures that leave trails of ruin behind them, but would fancy putting
longstrider (self only?) on the list to give the shaman a bit more mobility. Although we could just give it a higher base speed like a Barbarian rather than bothering with a spell.
Maybe a few utilities like
detect magic and
detect poison and disease to cover its shamanic duties. As it's a
beast shaman one would expect some "animal spells" such as
speak with animals,
locate animals or plants and possibly
animal messenger?
If we're going higher level utility, my favourites are
scrying and/or
contact other plane (I doubt a gnoll shaman would have
commune with nature like a druid, but it's quite likely to contact demonic forces instead!).
For combat effective spells, I'd put
dispel magic high on the list. That's always handy for a caster.
Not feeling very inspired for other combat spells, but that's probably too many already already.
Going by SRD precedents the Innate Spellcasting list should be pretty short, no more than five or six in total.