Preston Garvey, Minuteman

At the beginning of combat on your turn, create a green Aura enchantment token named Settlement attached to up to one target land you control. It has enchant land and "Enchanted land has '{T}: Add one mana of any color.'"
Whenever Preston Garvey attacks, untap each enchanted permanent you control.

Golden-Tail Trainer

Aura and Equipment spells you cast cost {X} less to cast, where X is this creature's power.
Whenever this creature attacks, other modified creatures you control get +X/+X until end of turn, where X is this creature's power. (Equipment, Auras you control, and counters are modifications.)