Icthellid being undead means he can be an interesting pick for the Necromancer's Undying Servant. It can spend its egg then when the Necro reanimates it, it brings new egg into play since it counts as a resummoning.
Or, attack your own friendly living creature.. put an egg in it, toss it away with sacrificial altar .. get a melee boost and another death-spider.
And of the larve is a poison condition, so the Necromancer can use plague master to deal direct damage every turn to speed up the hatching process too.