Pandora, in some thread (I don't remember which one), you wrote that summoning triples your army, and some guy wrote that it's good to earn Vampires by fighting neutrals. I agree that summoning triples the army, but it's a pity that they don't stay after the battle... But Vampires increase the army itself... so the expression "tripling" is more suitable for Death, or rather, for Vampires!

No, no. I'm not saying that the hero skill "Summoning" (not the spell!) triples the Druid's army. I'm talking about three things: the portal, the "Summoning" skill, and summoning spells. That's what will triple the Nature army.
It doesn't fit Death. She only has necromancy, with which she can replenish her forces, and that's it. Yes, replenishment remains, but Nature will also have those who came from the portal and those who came with the help of the "Summoning" skill. That is, two squads. And since Death can't summon anything worthwhile without a Demonologist, she is definitely at a disadvantage. After all, a Druid, without leveling up his second skill (for example, that of Death or Order), can already summon excellent creatures!

and doesn't the "Summoning" ability summon random monsters?

Yes, random ones. But, it seems, from the third level of "Summoning," the Druid will summon elementals. He may summon something unnecessary at first. For example, I don't like Earth and Fire elementals very much, so I just dismiss them and wait for the next turn. I wait for Water elementals... and then it's smooth sailing.

Request: "Where can I get cards with a skull on the emblem?"

What cards are you talking about?