@Fahrenheit
Well to minimize chaos and people slowing down due to spam of "snowflake trail mode", players who step this trail will not automatically be slowed down, it's a matter of chances that can be affected by it. So I would say that it's a 1/4 chance players who touch it will be affected by it?
About the lightning mode, I imagine anyone who touches this trail will be electrocuted.

New idea: The footsteps will be used as bullets. It'll have a freeze to decrease spam! Players tap the fire button and only 5 steps will come out. Yes this trail can harm them 1HP but the chances are still low to be slowed down. Slowing down will last the same as being gassed.