(This is a Noble Phantasm-in progress for a Servant I'm making, I just want to post it to others to see whether it's "overwanked" or not. If there are some problems, please point them out.)
Spider Bombs - Villain’s Cursed Legacy - C - Anti-Unit -
The Primary Noble Phantasm that Matsunaga Hisahide utilizes aside from his normal explosives. The NP is a manifestation and combination of his Three Great Sins and infamous death via explosion. These vile deeds take form as numerous small spiders that are formed from gunpowder with the Matsunaga crest on their back. Otherwise, these “bombs” just look like a smaller version of a common house spider.
When they’re deployed, these spider bombs will crawl towards their targets. Never stopping, they will get to their targets slowly but surely. When they arrive at their targets’ place of inhabitance, the spider bombs’ common tactic would usually be hiding within an item/apparatus (i.e. cups, remotes, keyholes) that the target regularly uses. And when the target either uses the item or apparatus, it triggers a 2 second countdown. After the countdown, the spider detonates, creating an explosion equivalent to a grenade’s. While this would deal relative damage for a Servant, this would certainly be lethal for a Master.
Hisahide is allowed to deploy only a maximum of eight spider bombs into the field. If any of them is detonated/destroyed, he can recreate them 3 minutes later. These spider bombs aren’t controllable under the Familiars Skill, so they can only track down their targets by sensing the specific sound waves that they emit. Because of this, if the target ceases to make any sound, the spider bombs will have no idea where to crawl. However, if anyone tries to crush them before they reach their target, the spider bombs will detonate immediately.