how should i combat the monster i am tracking

[Nosta]

so I am a level 12 sorcerer-rogue swift blade gestalt

I have a wand bracelet with a +1 holy a +1 lawful bane +1 chaotic bane and a +2 spell storing (all short swords)


I have a arm bow with quick loading.

I mostly have transmutation and conjuration spells as my spells known


the monster in question is a
wyvern that has the following templates half red dragon, blooded one half fiend and 13 level of DFA

[Gallowglass]

Wait. You are 12th level and you are hunting a half dragon/half fiend with 13 class levels on top of it?

How should you combat it?

With friends.

[Bronk]

so I am a level 12 sorcerer-rogue swift blade gestalt
I have a wand bracelet with a +1 holy a +1 lawful bane +1 chaotic bane and a +2 spell storing (all short swords)
I have a arm bow with quick loading.
I mostly have transmutation and conjuration spells as my spells known
the monster in question is a
wyvern that has the following templates half red dragon, blooded one half fiend and 13 level of DFA

I think it would have been do-able without the half-fiend, because there are a number of spells (like shivering touch) that could one shot it fairly easily, but considering that it now has SR30 and with blasphemy and destruction SLAs due to it's 20HD?

I think your character is out of it's league with this thing in a one on one fight, so I would say: maybe stop hunting it until you level up, or get lots of help... maybe 20 or so archers with magic arrows, keeping their distance.

(Or, you could argue that because the 'blooded one' template is only for humanoids, it should disappear in a puff of logic!)

[Gildedragon]

The monster is approx CR20, taking into account that you are gestalted AND assuming the levels are nonassociated (CR 6 (wyvern) + CR 3 (first 6HD of DFA) + 7 (last seven HD) + 1 (blooded one) + 2 (half fiend; assuming it doesn't count the class HD) + 2 (half dragon) - 1 (gestalt) = 20; 21 if half fiend counts the class HD)
Even with a party at your level you probably won't make it out easy.
Alone: ya ain't gonna make it.