Road to Legend - monster upgrades

By JezusCorp, in Descent: Journeys in the Dark

Hi,

My question is the interpretation of the Overlord upgrade phase. In the rulebook, it says

The overlord may buy one (and only one) of the upgrades

described below each game week using his XP. This occurs in
the Overlord Actions game week step, after lieutenant actions
have been carried out. Note that spending XP only affects the
overlord’s current XP total, not his conquest token total.

Can the Overlord upgrade more than one type of monster during the same monster upgrades phase? For exemple, at the first overlord upgrade phase in silver level, if the OL has enough XP to upgrade both Beast and Eldritch, can he do it in 1 week or in 2 weeks?

Thanks

Edited by JezusCorp

No, he can't. He needs 2 weeks.