At-will, swift, ranged, wall 1/level, concentration; a wall of chosen color (from your palette) blocks effects based on that color, and has effects on whatever crosses based on that color.
Red
Rank
Blocks
Crossing
1
Physical missiles
Medium force damage
2
Unattended, nonmagical objects
Energy attacks reduced by 50%
3
Creatures (Str negates), fluids
Heavy force damage
4
Gases, plasma, anything with mass
Energy attacks reduced by 100%
5
All physical matter, energy, and forces (including light)
Green
Rank
Blocks
Crossing
1
Toxic gasses
Medium poison damage (plus poisoned condition, Con ends)
2
Metal-forged weapons, armor, constructs
Heavy disintegration damage (rust)
3
Toxic fluids
Heavy poison damage (plus poisoned condition and medium poison damage, Con ends)
4
All artificial objects
Nonmagical items destroyed
5
All impurities (organic life passes through; objects, toxins, etc are annihilated)
Blue
Rank
Effect
1
Damaging attacks crossing the wall are reduced by 5 damage per rank
2
Saves against hostile effects crossing the wall are rolled with advantage
3
Hostile spells are counterspelled (your DC)
4
Any crossing effect that kills you instead drops you to 1 HP