PvE combat in Canopy mainly takes the form of mass scale tower defense, where enemies swarm across huge sections of the sector striking multiple nodes viciously and indiscriminately. So while Seekers need to defend their nodes against other Seekers, everyone will also be facing the existential threat of the Daemons.
The Daemons take their name not from the classic horned devils of religious lore, but from the more ancient Grecian pagan mythos of animist spirits found serving all manner of forces of nature. Inevitably, Maev found and cultivated them, manipulating the negative energies left from the Cataclysm to fashion them into war servants carrying out her malice.
There are an assortment of daemon creatures that Maev will attack Canopy with, each requiring different tactics to combat effectively. For example, the Furies are the most basic daemons. Individually weak, they rely on sheer numbers like a school of fish to get near and attack the nodes into submission.

Meanwhile, the less common (but more terrifying) Karies lurk amongst the Furies, and may suddenly soar out to suicide-bomb nodes for huge damage.

There are many more creatures, including incredibly powerful ones that could potentially smash through every node in their path. Worse, daemons of different types can synergize their abilities to make surviving the swarms even harder. It’s even hypothesized that there may be daemon leviathans epic enough to threaten the very existence of Canopy itself.
There are two types of daemon incursions that Maev orchestrates. First, she can spawn a rift anywhere, from which flow all manner of creatures in every direction. Secondly, she can create a path of destruction where a flood of daemon travel between rifts.

Moreover, Maev is intelligent and hateful, and tends to direct her minions to inflict damage at the nodes (and Seekers) who seem to defy her the most. Never get comfortable; Maev abhors your peace, and covets your tokens. As an AI agent herself, we can arm players, but we can never know exactly what she may do.
Fortunately, a wide array of weaponry will be available to fight them, so the harder question is if one wants to help in the war effort alongside Seeker brethren… or be the scavenger who swoops in for the aftermath to take advantage of the ruined.