Enduring Ideal has been one of those cards that Modern brewers have targeted over the years that has yet to pan out. Years ago, it was the central piece of a combo deck in Extended, using the fast mana of Lotus Bloom, Pentad Prism, and Seething Song to power out the sorcery as early as turn three.
As it turns out, casting one spell a turn for the rest of the game can be effective so long as it's the right one. The first two instances of the spell typically find Dovescape and Form of the Dragon, at which point you need only find ways to stall the game long enough for the five damage a turn from Form of the Dragon to kill your opponent.
This deck isn't so much as looking for speed as it is looking to grind the game to a screeching halt. Ghostly Prison, Porphyry Nodes, Leyline of Sanctity…these are not the cards of a player who wants their opponent to do much of anything. You're really acting like a control deck here, answering all your opponent's threats and building to your end-game before they can break free of the soft lock.
That end game is the typical Enduring Ideal / Dovescape / Form of the Dragon kill, although you can continue finding lock pieces to stabilize your position before actually going for the kill. Notably, one of the ways the combo is vulnerable is from the opponent simply casting spells into Dovescape and killing you with Bird tokens, made much easier by Form of the Dragon giving its controller a scant five life. This deck is going to be excellent at thwarting that plan by finding Ghostly Prisons and Phyrexian Unlifes until there is absolutely no hope.
I'd be remiss if I didn't point out the synergy between Phyrexian Unlife and Form of the Dragon requiring your opponent to deal fifteen damage divided into two appropriately sized chunks. I don't know if Dragons and Phyrexians have a history, but they appear to work well in tandem.
Of course, Modern is a fast format, and sometimes this plan of bogging the game down might get overrun. For games like this, you have Nykthos, Shrine of Nyx to accelerate your gameplan and either spew your hand of enchantments onto the battlefield or cast Enduring Ideal much faster than your opponent could've anticipated.
That'll teach them for trying to actually play Magic.