Witnessing the bloody execution of Jarl Borg, Torstein, battle-hardened warrior that he is, is nonetheless as shocked as he is amazed by the gruesome spectacle. Torstein is seemingly killed by Floki with poisonous mushrooms in an effort to win the trust of King Horik.

Do they find out Floki killed Torstein?

Torstein was presumed dead when in season 2's finale Floki poisoned him with mushrooms, but it turned out that these only made him appear dead, and he was revealed to be alive later on in the episode (while also showing that Floki never betrayed Ragnar).

What did Floki give to Torstein?

Floki continues to be busy. He secretly gives mushrooms to Torstein, one of Ragnar's most loyal and fierce warriors.