Olympus has Falllen

Just for cooldown

Because of Spear of the Magus third and the fact that Book of Thoth and Book of the Dead are in the build.

Lategame you can sell Magus for Obsidian if you want.

I feel it's absolutely valid for Zeus. He's going to deal multiple instances of damage, and finish off with Detonate Charge. In many instances, the enemy will be at < 1/2 health at that point, triggering the power boost.

Although Bancroft's Talon is absolutely a functional item, I also think Soul Gem could be considered instead. A single Chain Lightning should be able to build stacks, and then Detonate will get the heal off, not just for him, but for nearby teammates. That passive portion is a heal, rather than lifesteal.

For Zeus, all lifesteal items are less effective, at least to a degree. Why? His abilities are AOE/multi-target. This means the lifesteal has a 0.33x coefficient (only 1/3 the original amount). This is okay, because he's more likely to reliably hit multiple targets, allowing the damage to ramp up and still get good lifesteal...but it's something to consider.

This might work so ill give it a try

As per our Poseidon discussion, I think Spear of the Magus is a bit too early for my personal taste.

If I get Divine Ruin and Shoes of the Magi somewhere in my build, I might as well just get Spear of Desolation instead of Spear of the Magus.
That gives me a total of +40 flat magical penetration, which is enough for most squishies.

But again, it depends completely on the enemy comp. If enemies have 2+ front liners, +40 flat penetration will only tickle them. So Obsidian Shard needs to be considered as well. I would never buy it in the same build with Spear of the Magus. I miss the days when Obsidian Shard had +33% pen.