I have totally done this, because if I remove the blight I have to somehow get it back if I want to use my powers there.
I think I like the idea of losing due to blight with Wildfire (if Wildfire causes the blight that loses the game) is the spirit finally just giving up being careful and just lighting the whole island ablaze.
The easiest way to do this is add your presence to an adjacent blighted land without your presence. This will cascade a blight into the land you wished had blight, but it won't destroy your presence because the blight was from you. That's a net +2 blight instead of +1, but it creates a land with 2 blight in it, which is very easy to clean up using your innate power.
This makes me happy. 
(The Blight that Wildfire puts down represents actively burning wildfires.)
As I've tried to tackle a couple solo 4-spirit games, I'm finding that the biggest trouble I'm having with Wildfire so far is that the blight he spreads destroys other people's presence, and figuring out how to work around the combination of that and the (blight + your presence + invaders) requirements to some of his powers.
I tend to just tally things up differently to help my mental models. I count any Invaders in blighted lands where Wildfire is as effectively destroyed already (and will be finished off at my leisure). Then I look for other things to do, and finish off those foolhardy invaders as I get a chance.
Yeah... but then as I've looked for places to spread to, what I've found is that often the places I want to be have somebody else's presence there already, and I've got two Fire symbols on my track - so spreading there will place blight, which will destroy their presence.
I'm probably having more trouble with that than anything else.
Yeah, part of Wildfire seems to be other people leaving you space to deal with yourself. Wildfire does not play nice with others.
On the other hand, Serpent occasionally finds Wildfire a useful bedfellow; the odd destroyed presence means it can get more onto the board without having to nom on others.
I had amazing game last night where minor spirits gave Wildfire the gift of the "+2 range" minor power. The invaders didn't last long when it could start flinging fire everywhere.
Wildfire was originally rated High complexity for this reason - it changed the game for other players as well as yourself. But it doesn't do so as much as the other High-complexity spirits, and enough testers said it felt more Medium to them that I dropped it down a notch.
If you're in a game with Wildfire, it can sometimes be useful to follow them into hotspots - they'll already have Blighted, and it leaves the surrounding lands clear for additional Blight. Of course, this doesn't help if they heal and then re-Blight the land, but when playing with fire there's always the chance you'll get burned.
Also, if you're sitting down at a game with Wildfire, you can prioritize "get more Presence out" more highly, both because Wildfire's apt to destroy one or two along the way, and because the Blight card is likely to flip a bit faster which means your Presence is more at risk (from ongoing Blighted Island effects, or the "add Blight or destroy Presence" Events).
In the sense of Wildfire destroying Serpent's presence?
Or can Serpent nom on destroyed presence? (I don't think so, but don't have the power card in front of me, either.
It would mostly have to be with Wildfire destroying Serpent's presence.
I found, at least in a couple 2-spirit games, that Wildfire pairs well with Rampant Growth. (which actually makes a lot of sense if oyu think about it)
Rampant Growth really doesn't care too much about losing presence (unless there is a need to have a sacred site to prevent Invader actions in that particular land). And, rampant growth always gets at least 1 presence out each turn, regardless.
Reaching Grasp and Entwined Power are so good for Wildfire. Reaching Grasp is particularly good for clearing a land of Blight so that when you place Presence into it the Blight won't cascade.