From FP to potential patch, a modder should...

[Awachi]

... account for checks becoming unnecessary? 

LSS:  is there something I can do now writing a mod that will help its transition to the next patch? And remember, I am an idiot. 

[CamDawg]

Honestly not too much, especially right now when it's a moving target.

I think there will be two main changes that will affect modders, at least in terms of spells and items:

• We're making finer distinctions between the usage for paralysis (op 109), web (157), hold (175), and immobilization or special hold (185). See any number of threads from DavidW about these. These were fairly distinct back in oBG and have become increasingly intermixed as time has gone on (this is something that BG2FP will also have to untangle).
• How immunities in general will be structured with spellstates rather than direct opcode blocking. For example, being immune to charm used to be an immunity (101) to the charm opcode, blocking charm-related portrait icons, blocking strings like 'charmed', blocking visuals associated with charm, and so on. Now immunity to charm will basically set a CHARM_IMMUNITY spellstate, and charm spells will not apply (via 318 or 324) to creatures with this spellstate.

As above, though, I wouldn't start making changes yet--we're still working towards a release and things will likely change. As things settle down, we'll try to put out a modder's guide about changes you should be considering.