Activate Zameck Guildmage's first ability by paying ({G} magic symbol) ({U} magic symbol) , causing each creature you control to enter the battlefield with an additional +1/+1 counter this turn.
Activate Phyrexian Altar by sacrificing Grazing Kelpie, adding one mana of any color.
Grazing Kelpie dies, triggering its persist ability, returning it from your graveyard to the battlefield with no -1/-1 counters due to Zameck Guildmage.