Bristly Bill, Spine Sower links land development to a growing counter army. Each land entering under your control places a +1/+1 counter on a target creature, while its five-mana activation doubles the +1/+1 counters on every creature you control. The inexpensive casting cost lets Bill begin accumulating value early, then turn excess mana into a much larger battlefield later.
Fetch lands provide two separate land entries and therefore two opportunities to place counters. Hardened Scales and Branching Evolution increase the counters supplied by those triggers, helping establish a stronger starting point for Bill's doubling ability. Kodama of the West Tree is another useful partner because counters modify your creatures, letting successful attacks search for additional lands and create more Bill triggers.
Distributing counters can be better than concentrating everything on one threat. A wider set of modified creatures benefits from each doubling activation and reduces the impact of a single removal spell. On the other hand, growing an evasive attacker may be the fastest way to finish a game when opponents cannot block it effectively.
The activated ability has no tap requirement, so you can use it more than once when sufficient mana is available. It doubles the counters already present rather than adding a fixed amount, making the initial counter supply important. Keep some protection available when possible, and choose whether another activation or another creature will create the more resilient attacking position.
