In the WotC forums I would often simply post threads with one or two random card ideas on and let them simmer. Upon inspection I see that that doesn't happen very often in NGA so I've decided to create my own thread specifically for various random cards which I summon. These cards aren't for any set so I will leave out rarities (also, don't expect to see any link between them).
Here's some:
Stratovolcano
Creature - Elemental Incarnation
~ enters the battlefield tapped.
At the beginning of your upkeep put a 1/1 red elemental creature token with deathtouch named Lava onto the battlefield. It gains haste.
At the beginning of your end step, sacrifice each creature you control named Lava. For each creature sacrificed this way, you may put up to one +1/+1 counter on ~.
5/5
Schildvulkan
Creature - Elemental Incarnation
At the beginning of your upkeep put 2 1/1 red elemental creature tokens with deathtouch named Lava onto the battlefield. They gains haste.
: Put a 1/1 red elemental creature token with deathtouch named Lava onto the battlefield.0/7
Eruption
Instant
As an aditional cost to cast ~, sacrifice three elementals.
~ deals five damage to each creature and each player, creatures dealt damage this way can't be regenerated. If a creature dealt damage this way would die this turn, exile it instead.
Molten Stream
Creature - Elemental
Defender, deathtouch.
: Put a 1/1 red elemental creature token with deathtouch named Lava onto the battlefield. Activate this ability only if ~ hasn't blocked this turn and only after blockers have been declared.1/8