The idea is good, but your exact numbers are, in most cases, seriously underpowered, especially for vanilla creatures. You should compare your values to currently existing cards; many of them are strictly worse than existing cards. For instance, would you rather use a 4
cost hematite golem that is 4/6, or a weaker 4/5 creature costing 5
? It's pretty much a no-brainer.
4
4|4 Boring, but it would be a fair card. It would be hard to justify over abomination, though.
5
5|3 Will never ever see play due being strictly worse than mummy
5
3|8 Will never see play due to chargers and even graviton mercenary being better
5
4|5 Will never see play, strictly worse than hematite golem
4
4|5 Will never see play, worse than frog/cockatrice
5
6|1 Weak, but could conceivably see a bit of play
7
6|6 This is your best one by far, because light has nothing like this unupped
5
5|3 Probably won't see play, overshadowed by wyrm
5
5|3 Will never see play, strictly worse than toadfish
5
5|3 Weak compared to ghost of the past, but could conceivably see some play
5
5|3 Will never see play, strictly worse than gargoyle
5
3|1 immaterial This one could conceivably see play as a cheaper version of immortal, but immortal is already basically a vanilla creature in the same vein