The short answer is that it would take two game weeks.

Your first quote is the important one. From page 24 in the Rulebook (Overlord Upgrades)... "The Overlord may buy one (and only one) of the upgrades described below each game week using his XP."

It will take one week to upgrade the Beast monsters, and a following week to upgrade the Eldritch monsters, even if you have enough XP to upgrade both of them. Hope this helps.

Hi Cejel,

Thanks for the answer, even though it does not help me at all!

But, i would like to point something. In my second quote, it never says that there is a limitation in the number of upgrades we can make per week. The rule only says that there is a limitation on the number of monster categories (copper, silver, gold or diamond) depending on the campaign level!

Am i the only one seeing it that way? By the way, it is the same for treachery upgrades (see quote)

The overlord can use XP to increase his treachery. The cost to

purchase one point of treachery of a given type, as well as the
maximum number of points of each type the overlord can have,
vary based on which Avatar the overlord has chosen. Both
values are listed on the Avatar sheet.

Treachery works best with the rules presented in The Well of
Darkness and The Altar of Despair. Players without either of
those expansions, however, can use the rules found under
“Simplified Treachery,” on this page.

If we read the rule of this type of OL upgrade, we understand that there is a limitation on the maximum of treachery points the OL can have, NOT on how many points he can buy in a week!

Even more, it is the same for the avatar upgrade (see next quote)

Avatar Upgrades are represented by Avatar Upgrade cards.

There are 15 generic Avatar Upgrades that any Avatar can be

upgraded with. (These say “Any Avatar” on them.) There are

also five Avatar Upgrades specific to each Avatar, which can

only be purchased when the overlord has chosen that Avatar for

the current campaign.

Avatar Upgrades can improve the Avatar itself, upgrade a

specific type of monster, or bring into play a lieutenant for the

overlord to command.

The XP cost of each individual Avatar Upgrade card is listed on

the card itself, in the upper left corner. Once the cost is paid,

the overlord takes the card in question and keeps it faceup on

the table during play.

We must understand that when paying the cost of an upgrade card (cost written in the corner of the card) the OL takes it and keeps it face up during play. It does not say that the OL cannot buy more than one avatar upgrade in a week, if he can and wants!

Finaly, let's come back on my very first quote (see quote reproduice below)

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.

This particular rule says that the OL can buy one (and only one) TYPE of upgrades described using his own XP. As i mentionned here, each type poses no limitation on the quantity per week!

So, am i right in my interpretation of the rules?

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.

This particular rule says that the OL can buy one (and only one) TYPE of upgrades described using his own XP. As i mentionned here, each type poses no limitation on the quantity per week!

So, am i right in my interpretation of the rules?

Sorry but the word TYPE you highlight does not exist in the original quote. The rule says the Overlord can buy one (and only one) of the upgrades described below each game week. It can't be any clearer: one and only one. Not one of each type and not some of one type.

Sorry JezusCorp, but Ispher is correct. ONE upgrade each game week, not one upgrade of each type.

Each week you may upgrade ONE monster group, OR purchase ONE avatar upgrade, OR purchase ONE treachery upgrade, OR purchase ONE plot upgrade. The original second quote you mention is the overall total upgrade limits for each type, which is not quite the same as how and when you can get them.

If this isn't clear by now, we're gonna take our turn, roll the dice, and send a horde of skeletons, beastmen, and spiders your way, and they will tell you in their own terms!!!