So if I band to draw a lost soul do all the extra stuff then the band is negated the ls goes back but the ls ability doesn’t get negated..?
If only the band is negated does the draw ability even get negated?
If cascade negate is officially gone, then the rule is this: When you activate a negate ability, it only negates the ability (or abilities) it actually targets, and nothing else.
In your example, it's simple. An ability (like maybe 12 Fingered Giant) activates. 12FG says "Negate Band abilities". Therefore, it negates (and ONLY negates) band abilities.
Every other ability, whether a Draw ability, whatever the LS ability was, etc. is unaffected if it isn't a Band ability.
The new way of thinking is simple: Identify which abilities are targeted by the negate. Then undo those abilities. Don't do anything else.
In other words, do what the card says, and only what the card says