So I've been playing my apocalypse discard deck. No hela, ghost ride, dracula. I've been the first to fill up the raft a few times. Got Hela 3 times now, a Galactus, and 1 giganto.

I played Lady Sif as my last raft card, got Hela. The when Sif went to discard she discarded Hela over the 3 drops in my hand. Fine since she technically costs 6.

Another game I play Colleen Wing last to fill up the raft and get Giganto. I was hoping to discard the 2 cost swarm in my hand but to my surprise it discarded the now zero cost Giganto.

So cards from the Raft are both the highest and lowest card at the same time. Not game breaking or anything but an odd interaction for sure.