How were the Seer's prophecies to Lagertha realized?

In Vikings S3E1 "Mercenary", the Seer says to Lagertha:

I see a harvest celebrated in blood. I see a trickster whose weapon cleaves you. I see a city made of marble, and a burning, broiling ocean.

I think the trickster is

King Ecbert (edit: or Kalf), who had an affair with Lagertha

and the city made of marble is

Paris, obviously

But I don't understand the other two. My best guess for the harvest celebrated in blood is

the failure of the crops in Iceland in season 5, putting the settlers at each other's throats

but Lagertha wasn't there for that.

vikings

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Ubbe wakes up in the middle of the night, and he hears voices; the Seer tells him he should leave their new place.

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