Forgotten Creation

Oracle Text
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.
Card Rulings
4/8/2016 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.
4/8/2016 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.
4/8/2016 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.
What I've noticed is that when people talk about Skulk, they glaze right over it as just another little + in value but.. meh.
Read the ability carefully.. can't be blocked by a creature with greater power. To put it simply, increase the toughness of your skulk creatures by +0/+1 and they will never be blocked, or most likely trade up.