So if you chain them you can basically discacrd 16 cards in best case scenario? I really can't take your suggestion seriously...
Edit: Oh you discard your Silencers as well, well that is super bad for the spell

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There are some subjective suggestions I feel, but that is hard avoid. For example I think Parallel is really strong and it is easily top 5 most annoying cards on my list, but I feel it's ok to be like that. What I don't like - because it can be really unexpected - is some of the outcomes that come out of it. For example I remember a game where Maraut copied/paralled Timea into my Phoenix and when I killed it, it turned into Timea again with her effect when you play her on top of that (+1/+1 on two creatures)... How could I have predicted that? He made a Phoenix out of it and when the Phoenix died it transformed back into the old card instead of another Phoenix? Hm... wait what. I expect the usual oldie to come and tell well Phoenix is your card so when it died it counted as yours so it magically transformed into the old card and so on... that doesn't even make sense

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As long as I can play stuff while opponent is ramping and not throwing Silencers in my face to cock block me and fuck me up the ass I am fine with New Horizons (maybe a 1 mana requirement or drain on next turn if it still feels too strong for other people). Silencer is bullshit/annoying card number 1(for me). People seem to mostly keep quiet about it...
As for detonate I think it came out rather good after the changes, I definately used it a lot (prolly too much). As for the Target emblem effect, I feel that most of the problem comes to the effect itself, not how it works with the card specifically. I found out - rather surprisingly - that you can't stack the outcome of the Target emblems. You can stack multiple on a single target, but when you use it - be that the hero specific shrine or detonate or others cards that have it, you get only the useage of one - so if you have 2 target emblems and you use to deal 2 damage you deal 2 damage for 2 targets emblems. If you dealth 4 it would've been much better and maybe make the mechanic actually useful.
Prin'ha - is alright? Actually I feel she is kinda underwhelming a bit. First time I played her I thought she is cool but learned fast that if she is udner a card and this card is killed by deadly she dies as well (or enemy kills his creature) - which at that point in my mind it didn't make (and I still don't like it) sense.
Forgot about Trigon - how about when you lvl up you can only use the first colour this turn and the second on your next? It is kinda clunky, but just giving idea.