D&D 5E Warlock's Frost Lance Query

[Amatiel]

Frost Lance is a warlock invocation from the wotc-UA. Now, is there any way for 5e warlock to make his eldritch blast inflict cold damage instead of force damage. I can't find one, but thought I would ask and see if anyone knows of a way. Lots of ways back in 3.5e, but that was a differrent beast. I suppose I could make a feat or something, but thought I would see what people's thoughts are on the issue. ?

eFROST LANCE (Invocation)

You draw on the gifts of the Prince of Frost totrap your enemies in ice. When you hit a creature with youreldritch blast cantrip one or more times on your turn, you can reduce thatcreature’s speed by 10 feet until the end of your next turn.

 

[Hawk Diesel]

Personally, I have no problem allowing a player to switch the energy type of their spells as long as it never changes after that. You want eldritch blast to deal cold? That's fine (especially since force is generally viewed superior to other damage types). But you make this choice when you first gain the spell and it remains that way until you have a legitimate reason to switch it out (ie learn a new cantrip, have some sort of energy Substitution ability, ect).

 

[cbwjm]

For an invocation like frost lance, I think it would be appropriate for it to change the damage type to cold if you use the invocation. Personally, I'd probably change it so that it must be cold if it is used so the player can make the choice of force damage or cold damage and the slow effect each time they cast the spell.