Lets say I have greenbelt rampager in my hand and I want to be able to repeatedly play it. To do so, I need to make sure I have less than 2 energy. So, if I had a demon of dark schemes in play. Can I attempt to use energy to activate the demon's ability even if I do not have enough to activate it?
Another example might be if I had a architect of the untamed in play. Could I attempt but fail to activate the ability and drain the energy that I have?
No. You cannot activate an ability/cast a spell if you cannot pay the full cost. If you attempt to do so, the game is rewound prior to the activation/cast.
In order to cast Rampager as many times as you have green mana, you would need an activated ability that costs E and doesn't require tapping, like Aethersphere Harvester (note: you don't have to crew it to activate the ability), Aetherwind Basker, Multiform Wonder, or Spontaneous Artist (note: you can give the same creature haste over and over again). (Despite fitting the bill on activation cost, Shipwreck Moray could only be used 3 times due to the nature of its ability, unless you can give Rampager flash somehow.)
In order to cast Rampager as many times as you have green mana, you would need an activated ability that costs E and doesn't require tapping
Note that if you have exactly 1 energy when Greenbelt Rampager's ability resolves, you will be unable to pay the cost of EE and will thus get a second E and bounce the Rampager. So this also works if you have a repeatable ability that costs EE to activate. Just not for a cost that requires more than two.
Another example might be if I had a architect of the untamed in play. Could I attempt but fail to activate the ability and drain the energy that I have?
In order to cast Rampager as many times as you have green mana, you would need an activated ability that costs E and doesn't require tapping, like Aethersphere Harvester (note: you don't have to crew it to activate the ability), Aetherwind Basker, Multiform Wonder, or Spontaneous Artist (note: you can give the same creature haste over and over again). (Despite fitting the bill on activation cost, Shipwreck Moray could only be used 3 times due to the nature of its ability, unless you can give Rampager flash somehow.)
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But this is a discussion for another forum!
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