When Arcane Shift targets my Mindsplitter and an enemy Watchful Sentry, does the Sentry's controller draw from Deathknell before Mindsplitter's 'When you play me' effect resolves?

Ruling: Mindsplitter's 'When you play me' ability resolves before Watchful Sentry's Deathknell. The opponent will discard a card from their hand before drawing from Deathknell.

Sequence:

• Play Arcane Shift, it becomes a pending item
• Finalize and resolve Arcane Shift in order: banish Mindsplitter, replay Mindsplitter (becomes pending), deal 3 damage to Sentry
• During Arcane Shift cleanup, Sentry's Deathknell triggers from the lethal damage
• Finalize pending items in FIFO order: Mindsplitter finalizes first, then Deathknell
• When Mindsplitter (a unit) finalizes, it auto-resolves and its 'When you play me' ability triggers, becoming a new pending item
• Continue finalizing: Deathknell finalizes, then the WYPM trigger finalizes
• Resolve the chain in LIFO order: WYPM resolves first (discard), then Deathknell resolves (draw)

Nuances:

• Pending items finalize in FIFO (first in, first out) order, but the chain resolves in LIFO (last in, first out) order
• Units auto-resolve when finalized, which can create new pending items during the finalization process
• Deathknell triggers are added as pending items during cleanup, before any pending items finalize