Caltrops

Whenever a creature attacks, Caltrops deals 1 damage to it.

Crossbow Infantry

{T}: Crossbow Infantry deals 1 damage to target attacking or blocking creature.

Towering Gibbon

Reach
Towering Gibbon's power is equal to the greatest mana value among creatures you control.

Elite Archers

{T}: Elite Archers deals 3 damage to target attacking or blocking creature.

Tower Defense

Creatures you control get +0/+5 and gain reach until end of turn.

Solid Footing

Flash
Enchant creature
Enchanted creature gets +1/+1.
As long as enchanted creature has vigilance, it assigns combat damage equal to its toughness rather than its power.