The Doctor is too angry to appreciate all the ironies. He is angry at himself most at all for missing the obvious.
Still there are many of life's little ironies that have happened recently. While all his enemies gathered it wasn't for revenge - well not just revenge. The Daleks were trying to save the universe.(Somewhat ironic. But after all, they do need somewhere to conquer). The second irony was despite all the warnings he had got incuding one from his subconscious he had refused to listen.
"Remember when you tried to chase down the Could Be King and his army of Meanwhiles and Never-Weres." the Dream Lord mocks. "Strange how you always make that gross error. I tried to warn you, you know. That was the reason for your nightmare. Not the dream pollen."
The next irony was also one the Doctor usually liked. An destructive being so caught up in their ego they never realise the trap until it is too late. (He's in a bad mood. But even this irony isn't the one he'd find the biggest if he wasn't the one who had been sealed.
Yet another irony was that the only reason he is a prisoner rather than Dead is because the Dalek's insisted. (Even they accept the Oncoming Storm has occasionally saved the universe. and while Daleks are never wrong their data may be incomplete. (And no, this isn't the irony the Doctor would find the biggest. Though it is up there.))
What the Doctor would normally find the biggest and best irony is that someone who would normally appreciate all these ironies is too angry to do so.
Then the door slowly opens...