That looks fine. The top ability is precisely Nephalia Drownyard but restricted to yourself, which makes it no good in offensive mill decks - which probably does mean it's okay to add the second ability on here as well.
The second ability is rather better than Volrath's Stronghold, but fairly expensive and requires two colours that aren't the same as the first one. It might still be a bit annoyingly grindy/repetitive, though. Perhaps it could either put the creature back on top of your library (at a reduced cost), or sacrifice to get back the creature (like Haunted Fengraf).
Hee! Looks like Commandeer at first, though it's actually more like Shunt. Nice.
See Death of Rats.
And also an artifact.
Etherium Sculptor was cheaper, bigger, and more common.
For just one mana, you can get Thran Turbine; doing something like this for 5 needs a much better payoff.
Given Frontier Siege, something of that cost should really add it at the beginning of each main phase at least. Also there isn't much blue involved.
Does this need "This mana doesn't empty from your mana pool as steps and phases end?"
Yeah, this would almost certainly appear at least at rare in a Wizards set, if that second ability would appear at all.
Shouldn't it be rare? I mean, Nephalia Drownyard and Volrath's Stronghold are both rare, and this is almost both those on the same card...
That looks fine. The top ability is precisely Nephalia Drownyard but restricted to yourself, which makes it no good in offensive mill decks - which probably does mean it's okay to add the second ability on here as well.
The second ability is rather better than Volrath's Stronghold, but fairly expensive and requires two colours that aren't the same as the first one. It might still be a bit annoyingly grindy/repetitive, though. Perhaps it could either put the creature back on top of your library (at a reduced cost), or sacrifice to get back the creature (like Haunted Fengraf).