I've found a very simple Host and Tempo which can make beating Seconds and obtaining Subject relatively easy, that being Visitor and OC Gold. This does mean you need the HoT gamepass, since Gold and Overclock both are locked behind it.
Visitor is quite strong, outputs good damage, and has abilities which can ambush enemies which are known for blocking attacks.
Gold is very useful for making decisions and doing combos decisively. It becomes exceedingly useful once you Overclock it, as it lets you dodge otherwise impossible attacks as well as attacking at almost no cost of your own, on top of an indefinite amount of time to decide what to do.
Visitor's beam synergy with OC Gold is absolutely insane, since you can stack lots of damage at once and the charge required to complete the beam attack is very little.
This is actually how I finally got Subject, since I was needing to know how the Host works and Mours was put offline for updating, so I couldn't use that game.