Tagg101, my uneducated guest judging by the way you have equipped your Ignatius is that this is more of a stat problem than champion or affinity related issue (though affinity does greatly add to your problem) and Stag Knight can't make much of a different anyway.
You can't race against Spider with 125 speed. I get it it's only Spider 11, but this is just too low even for stage 11. If you have this similar approach for your other heroes too - boosting their primary stat in expense for speed and/or accuracy, then your champions most of the time are watching rather than engaging in battle. And if they happen to act, and if they didn't land weak hit and they have good roll to land debuff and then they got resisted... i would be mad if i were you.
My humble suggestion to you to get to next stage is to begin by rethinking your approach to equipment. Get rid of that boots with def and find something with speed as primary stat. Try to at least double your added speed and if you find your debuffs got resisted (they resisted Ignatius Provoke and HP Burn, Tayrel's one or both debuffs and especially his and Coldheart's turn meter) then you have to correct that too by adding more accuracy. You can't do anything against RNG and bad rolls when you fight strong affinity, you will have weak hits almost 1/3 of the time, but when you have normal or crit hit and good roll, you have to be sure your debuffs would not be resisted.
Saying that, I do thing you have the team to beat stage 11 and you don't need Stag Knight services just for that stage. If you want to build him - good, he is one of the better epics, but first run through your equipment and try to boost your speed (and accuracy if needed). Then run again your regular team and observe the spiderling priorities and who they attack, how the battle have changed from your last run, when you die and why, is there something you can improve. Also, if you plan to use Apo, he need some serious equipment and babysiting, he is probably one of the spiderling's favorite, i guess.
Also, I take for granted that the others besides Tyrel are mastered too, right? Otherwise you make this harder than it is.
