Second run and I got a bit into endless with it somehow. Didn't think to take a picture, but I had 10 mana, the relic that replenishes three mana per turn, the relic that gives an extra energy, a book that converted two energy into four mana and increased damage of surrounding weapons by 2 per use, a crown that restored four mana when a wand killed something, a ring that gave four block for one mana, and a wand that base dealt 7 damage for one mana that I then buffed to like 16 with gems. So I had 18 mana first turn and 11 every after that. Free space was then just armour and roses for spikes.
Even the king at the end wasn't a threat, considering I had enough mana to just block everything and nuke summons, and my spike generation outpaced his regen. The run only ended when endless threw a pair of enemies that generated 21 spikes per turn at me. When your strategy is unleashing a bombardment of mediocre attacks, that enemy surviving one turn make them sort of unstoppable.