Spinebiter [New Phyrexia] Urza's Tower Set: Battle for Zendikar Type:

Set: Battle for Zendikar Type: Enchantment — Aura Rarity: Common Cost: {1}{W} Enchant creature

Her bold movements are anchored in the careful precision of each rope

Add {B}{B}{B}

{1}{G}: Anurid Swarmsnapper can block an additional creature this turn

But where is the source

Spinebiter [New Phyrexia] Urza's Tower Set: Battle for Zendikar Type:Set: New Phyrexia Type: Creature Phyrexian Beast Rarity: Uncommon Cost: {4}{G}{G} Infect (This creature deals damage to creatures in the form of 1 1 counters and to players in the form of poison counters.) You may have Spinebiter assign its combat damage as though it weren't blocked.