Cards that get MUCH more useful when being upgraded

[MHarmless]

Took me awhile to realize that not all upgrades are created equal, and I'm sure there are some out there I haven't stumbled on yet. Just a couple here

Settler - Settler card doesn't get redrafted, so upgrading it means all your settlers come with a free promotion. One of these promotions gives a free warrior, and it seems like there are only a small pool of options so at most one reroll will guarantee the warrior if it wasn't offered right away.

Volley - Volley seemed silly because lining them up is hard and 3 points won't do anything to a fortified opponent. The upgraded version, however, adds the 'keep' trait, so it sits in your hand until you use it. And the damage goes up. With two upgraded volleys you can keep enough firepower in hand to instantly eliminate almost any barbarian you can see.

What else have people found?

[mudrivercatfish]

Great observation ! I like the strategy of continuously upgrading one science, one production, one food and so on - and discarding the other weak cards. Some of the cards like science scale up nicely, in my opinion. Along with building solid income, there's good synergy to hit the breakpoints.

[Tiwaking! 56k NZ]

There is a relic card which upgrades all wonders. It is one of the best relics. There is also a relic which upgrades all of the cards you DRAFT which is incredible. Usually I will upgrade the basic cards (Toil first then Stargazer). Upgrading some of the initial buildings (Quarry and Timber) can get some resources very quickly.

The only card I can think of which is a must upgrade is Pave as it will return to your hand after use and has unlimited uses when upgraded. If combined with that Relic which grant +2 production per card played, you can use this card to increase production and upgrade other cards for as long as your wood allows.