On the other hand, i would happily have a card that discard a bunch of cards, deals damage AND summons a rare.
You continue to ignore you deal less damage the more you discard, you discard a very specific kind of card, and you don't even forbid your opponent Rare summons. It doesn't do all the above at once. You discard a bunch, OR deal damage, not both. If the opponent had more than four Dragons(Which is not an uncommon occurence against a dragon deck, esp. with Hydra in hand) You deal no damage.
All the above does is give the card variety. Against a dragon deck, Rexella discards. Against everything else, you deal damage. It's not a mode-esque option-fest where the cost of the two SHOULD be in part joined together, let alone two effects which are always active on a card. Most of the time, the discard is just hot air. When it's
not, it makes the damage hot air.
The main problem is that this card replaces itself. If you play it, you get another rare card.
...
Maybe. I still need to clarify just what you wish to accomplish, so, let's take a look at a close examples. Only three other rare Keyword summons exists(how oddo.o). I won't even touch Stonehenge for now, let's talk of Beast farm.
Beast farm costs 15 resources, spread across two- by pure numbers, also costs as much as a Scepter of Summoning.
But Beast farm also gives 13 +Wall along with the same kind of summons Rexella would do.
Now, uncommons receive less of a discount than rares, I presume? The 13 Wall is not for free.
How much of the card cost is worth the Rare Keyword summon, in your expert opinion?:3 Tis, adjusted to Rares, is what we should add to the cost of the other effects.