Found in the DS3 subreddit:
ネットワークテストと同様に、闇霊は協力霊がいるホストにしか侵入できないのですか?
いいえ。薪の王化したホストが干からびた指を使用するなどの一定条件により、協力霊のいないホストの世界に侵入できます。ただし、闇霊が数的有利になることはありません。
Can dark spirits only invade the world of host with white phantoms like in the Network Test?
No. Under certain conditions such as host in the Lord of Cinder using Dried Fingers, it is possible to invade the world where no white phantoms present. However, dark spirit will never have an advantage in number.
So they get rid of the worst PVP-related DS2 feature (Soul Memory) but implement something that can be considered even worse, 100% chance to encounter a gank squad?
DS1 system was perfect, you want to summon - you go human, but then you are vulnerable to invasions. And what's the point of the Blue covenant, if the person being invaded will be in 2:1 advantage to begin with?
Disappointed
![Frown :( :(](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7)