Cursed Flesh

Enchant creature
Enchanted creature gets -1/-1 and has fear. (It can't be blocked except by artifact creatures and/or black creatures.)

Living Armor

{T}, Sacrifice this artifact: Put X +0/+1 counters on target creature, where X is that creature's mana value.

Withercrown

Enchant creature
Enchanted creature has base power 0 and has "At the beginning of your upkeep, you lose 1 life unless you sacrifice this creature."

Locke, Treasure Hunter

Locke can't be blocked by creatures with greater power.
Mug — Whenever Locke attacks, each player mills a card. If a land card was milled this way, create a Treasure token. Until end of turn, you may cast a spell from among those cards.