Chris Sims for Comics Alliance:

“Ivar explains that pens and sunglasses always go missing because we’re constantly surrounded by wormholes through time that suck them in when we’re not looking.”

That’s enough for me. But wait, there’s more…

“Ivar shoots Horatio Nelson dead at the Battle of Trafalgar in 1805 (In our history, Nelson was killed by a French sniper). While there’s still a trace of that whimsical Doctor Who-inspired friendliness to the character, he suddenly becomes something a little more unknowable and a little more terrifying, a little harder to relate to.”

I never understood the Doctor’s aversion to violence, especially considering the scale of his opponents. Kate Stewart and War Doctor were right to sacrifice millions for billions in “The Day of the Doctor“. So was Harriet Jones in “The Christmas Invasion“. The Doctor must’ve learned something by Season 8’s “Mummy on the Orient Express“:

“I couldn’t save Quell, I couldn’t save Moorhouse. There was a good chance that [Maisie would] die too. At which point, I would have just moved onto the next, and the next, until I beat it. Sometimes the only choices you have are bad ones. But you still have to choose.”

Ivar, Timewalker (Fred Van Lente, Clayton Henry, Brian Reber, published by Valiant Comics) exposes everything right and wrong with Doctor Who, while being its own story.