Lairs are where hero levelling actually comes from, and Stamina is the budget you spend on them.
Antiserum (hero EXP) — is mainly obtained from
Beating Zombie Lairs on the world map. Hunting single zombies also gives it, and the Virology Lab is a slower secondary source.
What each source actually says
highgroundgaming.com
“your main source will be from beating Zombie Lairs in the open world map”
ultimateguidetopns.com
“you get WAY more antiserum from Lairs”
pns-mit.org · Japanese
“英雄のレベルアップに必要な「血清」”
Our translation: the serum needed to level up heroes
Stamina — is spent on
Attacking Zombie Lairs and hunting individual zombies on the map.
What each source actually says
ultimateguidetopns.com
“Zombie Lairs and good ol' fashioned Zombie hunting will use up stamina”
pns-mit.org · Japanese
“ギャザーを行ってスタミナを有効活用しましょう。”
Our translation: run gathers (lair rallies) to put your stamina to use
What we are not telling you, and why
Three things about lairs are documented in Japanese and nowhere in English we
could find. One source is not enough for this site, so they are not above:
Stamina's ceiling. pns-mit.org states a
specific cap. No English source gives a number, so we publish the mechanism and not the
figure.
Who gets wounded first. pns-mit.org sets out a
full casualty order by formation, and it is the most useful thing we read all phase. The
closest English writing is about a different subject, so it stays unpublished.
A level threshold below which nobody is wounded. Same problem: stated
once, in one language.
If you can point us at an English source for any of these, that is
the single most useful thing you could send us.
Lairathon is not a game event
It looks like one, and it is written up like one. It is a single alliance's own invention —
their guide says plainly it is “exclusive to TDS alliance which we run”. If your
alliance runs something called Lairathon, those are house rules, not game mechanics, and no
setting in the game corresponds to them.
Get answers where your alliance already talks
The bot answers these in your own server — /what covers the vocabulary and the FAQ answers sit behind it.