But its ability to force your opponents creatures to attack so that you can swing against an uncontested board on your turns really is fantastic
Beyond that triggered ability, Sixs main effect is likely giving all nonland permanent spells in your graveyard retrace, which allows you to replay them by simply discarding a land card from your hand in addition to paying their mana cost and any other costs associated with the card
These include creatures such as Agent Frank Horrigan (indestructible, proliferate), Alpha Deathclaw (destroys permanents), Consuming Aberration (mill), Ezuri (proliferate, card draw), Fathom Mage (evolve, card draw), Lily Bowen (+1/+1 counters, life gain), Marcus (card draw, +1/+1 counters), and many more
And while there are a couple of Clue cards that are artifact creatures, like Red Herring, by default most clues are just artifacts, not creatures