Houserule: what if Warlocks could replace all invocations on level up?

[Zaltman]

I like this too, it's basically "you can switch your invocations during downtime"; how useful it will be will depend on how frequent downtime is, I suppose.

Still at a cost (potentially needed healing) and only 1 x per rest. Gradual evolution not instant change. Like you I wanted to give a little more flexibility without breaking the class.