Forgotten Creation

Skulk (This creature can't be blocked by creatures with greater power.)
At the beginning of your upkeep, you may discard all the cards in your hand. If you do, draw that many cards.

Shadows over Innistrad Remastered

"My earliest work escapes me."
—Stitcher Geralf

Commander Legends: Battle for Baldur's Gate

Midnight Hunt Commander

Shadows over Innistrad

Shadows over Innistrad Promos

If you cause a creature to have 0 power or less, use the actual value (which may be negative) to determine whether it can block or be blocked. A creature with skulk and 0 or less power most likely won't be blocked, but it won't deal combat damage and won't trigger any abilities that trigger when combat damage is dealt.

Skulk matters only as blockers are chosen. Modifying either creature's power after blockers are chosen won't cause the attacking creature to become unblocked.

The upkeep step is before the draw step, after the untap step. If you have no cards in hand, you can't draw for the turn and then discard that card to draw a new one because Forgotten Creation's last ability will already have triggered and resolved.