From Archon Arcana - The KeyForge Wiki

When a player is instructed to shuffle their deck, they must do so in a manner that sufficiently randomizes the order of the cards in their deck so that the order of the cards in the deck cannot be deduced.

After shuffling, the player should offer their deck to the opponent to perform an additional shuffle and/or “cut”. To perform a cut, the player divides the deck into two piles, then re-stacks the piles in any order to form a single deck.

KeyForge Master Rulebook v17.3 March 2024