Whenever a creature you control with power 2 or less attacks, it gains skulk until end of turn. (It can't be blocked by creatures with greater power.)
Whenever a creature with power 4 or greater attacks you, its controller loses 2 life and you gain 2 life.
Deploy MacCready early and flood the board with small, evasive creatures (power 2 or less) that gain skulk on attack, making them nearly impossible to block. You chip in incremental damage with go-wide token swarms while the second ability turns opposing big attackers into a liability, draining them and gaining you life. Win by stacking anthems and team-wide evasion to alpha strike, or by grinding value off cheap creatures with sacrifice and recursion engines.
Cheap two-mana commander that immediately enables an evasive go-wide plan
Skulk makes wide boards of small creatures very hard to block and great for combat damage
Punishes aggressive tables and discourages big attackers from targeting you
BW gives access to elite removal, recursion, and token support
Synergizes naturally with weenie tokens, anthems, and aristocrats
Skulk only triggers on attack and only helps power 2 or less, so anthems can accidentally turn it off
Board wipes punish the go-wide strategy hard
Lacks built-in card advantage outside of supporting pieces
The second ability is purely defensive and irrelevant against non-combat or token-swarm decks
Individual creatures are weak, so the deck folds without a critical mass