When Saffi Eriksdotter enters the battlefield, Cadric triggers.
Holding priority, activate Honor-Worn Shaku's second ability by tapping Saffi Eriksdotter, untapping Honor-Worn Shaku.
Activate Honor-Worn Shaku's first ability by tapping it, adding C.
Resolve the Cadric trigger, causing you to pay 1 to create a token copy of Saffi Eriksdotter.
Activate Honor-Worn Shaku's second ability by tapping the Saffi Eriksdotter token, untapping Honor-Worn Shaku.
Activate Honor-Worn Shaku's first ability by tapping it, adding C.
Activate the Saffi Eriksdotter token by sacrificing it, targeting the nontoken Saffi Eriksdotter.
Activate Saffi Eriksdotter by sacrificing it, targeting Cadric.
When the nontoken Saffi Eriksdotter dies, the token Saffi Eriksdotter triggers, returning the nontoken Saffi Eriksdotter from your graveyard to the battlefield.
Repeat from step 3.
This clever loop relies on Cadric, Soul Kindler to bypass the legend rule and churn out temporary copies of Saffi Eriksdotter whenever she enters the battlefield. By weaving in Honor-Worn Shaku, you can tap Saffi and her incoming tokens as legendary permanents to continually untap the artifact for mana. Saffi Eriksdotter's own sacrifice ability then ensures an unbroken cycle of rebirths between the real card and its copies, fueling infinite creature triggers and an endless supply of colorless mana.