actually spells can have activated abilities, see lightning storm. but that's the exception, unless that's this block's theme. OP probably means abilities of cards in hand, like cycling.
This reads like it lets spend the mana on spells or abilities you control, which is OP and probably not what you meant. If you meant abilities of (permanents or spells), you can just say "Spend this mana only to activate abilities." The "you control" ability will almost never matter, and spells never have activated abilities.
Huh. Well, the name certainly fits: it's dependent on some other effect to make it any good at all. On its own it's worse than Darksteel Relic. However, that's not a good trait for a mythic to have. Mythics should stand alone, apart from extremely exceptional circumstances like Eye of Ugin. This looks like it should be a rare (if it should exist at all).
actually spells can have activated abilities, see lightning storm. but that's the exception, unless that's this block's theme. OP probably means abilities of cards in hand, like cycling.
This reads like it lets spend the mana on spells or abilities you control, which is OP and probably not what you meant. If you meant abilities of (permanents or spells), you can just say "Spend this mana only to activate abilities." The "you control" ability will almost never matter, and spells never have activated abilities.
Huh. Well, the name certainly fits: it's dependent on some other effect to make it any good at all. On its own it's worse than Darksteel Relic. However, that's not a good trait for a mythic to have. Mythics should stand alone, apart from extremely exceptional circumstances like Eye of Ugin. This looks like it should be a rare (if it should exist at all).