Implanter (Ziggurat of Apet), Thoughtform Minion?

[Shimrath]

Just prepping the Ziggurat of Apet for play. Should the implanters be thoughtform minions? Their flavor text says, "The ovipositor materializes solidly as it tries to burrow into your ear."

Would having to hit these minions twice effect the overall difficulty of this (seemingly nasty) combat encounter?

 

[Shimrath]

Also, the "attach" attack is essentially a grab. What should the DC to escape be?

I have read that you generally use a moderate difficulty DC based on the creature's level, but in a previous encounter the crawling spiker used an easy difficulty for it's escape DC. I suppose that matters of size and strength might change the difficulty.