Um; they are comparable in most games.

The times this is better are that this potentially lets you get to silly life, and you can gain even when the opponent isn't attacking - But the custodian is better when the damage is "in the form of" (e.g. EDH general damage, or poison) and especially lets you save your creatures - which is very very nice and against the NWO (but hey, this isn't common, so feel free).

So yeah; this is certainly comparable to the super-sammite. In may ways worse; but in one it's better, so there's nothing really wrong with that.

­Ghost-Lit Redeemer is cheaper; but costs to tap (so this goes large more easily) - Rejuvenation Chamber is crap.

­Zarichi Tiger is more expensive - but on a bigger body. But does suggest that this is, if anything, quite aggressively costed. Especially not having ANY activation cost is risky.

Then again, there's the artifacts - ­Marble Chalice is directly comparable; (but being on a creature body makes it riskier, so it's allowed to be better)

­Pristine Talisman is quite well regarded, and comparable.

­Clearwater Goblet says you can't price this too high; while Fountain of Youth says don't make activation too much either. Neither of those are great cards - Chalice of Life is usually going to be preferable to this.

So yeah, I reckon you are within the zone of life here. There may be tweaks plus or minus from paytest or set demands; but it seems plausible to me.

Agreed. But I think the power level between the two similar. Sometimes you'd rather be preventing damage, and sometimes you'd rather be gaining life. If I was to choose one over the other, though, you're right... I'd probably give it to damage prevention. Until you get into the higher numbers that is... I'd rather be gaining 4 life per turn than preventing 4 damage, for example.

This is utterly different from Sanctum Custodian. Preventing damage and gaining life are hardly comparable at all.

It seemed rather good to me... but that's more because we haven't seem this sort of thing in a long time. Took me a while, but I figured out the card to compare this to: Sanctum Custodian. The custodian currently has 3.1 to 3.4 stars, which infers that this isn't far away from being rather good... but probably does need a little bump. less might be too much. +0/+1 might not be enough. Don't know, really. +1 toughness and vigilance?

Seems underwhelming. I'd change it to target player to at least open up options in formats with multiple players in a game. And maybe drop the cost by

­Turnabout, because with the power of Urza, you can do anything!

Untap all my creatures is a "spider" effect (catch you when you walk into my trap), not "rattlesnake" (preemptively deter you from coming my way at all). You're right that it's most often white, but Vitalize exists, and... hmm... Deceiver Exarch, maybe? You're right, blue doesn't get as much mass-untapping as I thought.

Really?
Ok, first ability has many uses obviously.
Second ability.. oooh.

Turn 1: Forest, Bird of Paradise
Turn 2: Island, This in mode 2... [Bringer of the Red Dawn.

Turn 2 bringer! YAY! ... but this is a thing that's usually quite hard to manage on turn 3, so this might be better restricted to a single colour.

Anyway - untap all my creatures is a (usually white) rattlesnake; and a very good one. Still, even Rally the Troops and Call to Glory admits it's not a very expensive effect.

the third ability seems weak compared to the first two, pretty cool though

FWIW, you don't need to add italics around reminder text: Multiverse does that automatically, and adding italics manually cancels it.