"I need to take part in the war, or else my bones won't satisfy my needs for one year!" He looked at the Holy Ones bones and decided to stop using them.
These bones, alongside the dark realm ones, were his most precious assets. He didn't have another means to get them, at least for now. So, he decided to stick to using just normal bones, knowing this would raise the total cost to something scary.
He knew this was just the beginning. If he kept increasing the number of trees, investing everything he gained and got into planting more trees, then it wouldn't be surprising to use billions of bones to let the trees just grow up.
He wouldn't care if this was temporary, as the results were great. But this was going on like a snowball, with every new planting, more bones would be needed.
"I now realise why this heart wasn't that popular and the previous owner didn't keep it," he muttered to himself, squeezing his temples while feeling the pressure already.